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Applied Surface Science (v.271, #)

Editorial Board (pp. ii).

Research on cell behavior related to anodized and hydrothermally treated titanium surface by Chin-Sung Chen; Yuan-Li Tsao; Duen-Jeng Wang; Shih-Fu Ou; Han-Yi Cheng; Yi-Chen Chiang; Keng-Liang Ou (pp. 1-6).

► HYT surface could improve cell adhesion behavior by chemical property. ► Cell received larger stress stimulation in HYT group than in control group. ► Stress could cell growth by physical factor after cell adhered effectively.In vitro cell response is believed related to the physical and chemical properties of substrate. In this study, the cell adhesion affected by mechanical stimulation from substrate was evaluated by culturing the MG-63 osteoblast-like cells on Ti plates with different chemical composition and surface topography. Three types of surface, surface with machined grooves, with pores, and with pillars, was fabricated by mechanically abraded (control), anodized (AO) and anodized following with hydrothermally treated (HYT) Ti plates, individually. Cells exhibited earlier spreading on the AO and HYT surface after 5h culturing, resulted from chemical factor, i.e., calcium and phosphate containing on the surface. After 24h cells completely flattened on the HYT surface but not on the AO surface; this improved cell adhesion behavior was primarily attributed to physical factor that is specific surface topography provides cell relatively large mechanical stimulation. The finite element method was used to evaluate the stress distributions which cells were suffered. For the HYT group, analyzed data indicated that cell received larger stress stimulation than control group ( P>0.01); therefore it can explain the fact that the superior cell adhesion resulted from the specific geometry of HYT coated-surface.

Keywords: Anodization; Finite element analysis; Hydrothermally treatment; Stress

Microstructures of Ni–AlN composite coatings prepared by pulse electrodeposition technology by Fafeng Xia; Huibin Xu; Chao Liu; Jinwu Wang; Junjie Ding; Chunhua Ma (pp. 7-11).

► PED was used to prepare composite coatings on steel substrates surface. ► Effect of pulse current on the nucleation and growth of grains was investigated. ► Composite coatings consisting of crystalline Ni and AlN particles were fabricated by PED. ► Ni–AlN composite coatings by PED showed more compact surfaces and less grain sizes than by electrodepositing.Ni–AlN composite coating was fabricated onto the surface of steel substrates by using pulse electrodeposition (PED) technique in this work. The effect of pulse current on the nucleation and growth of grains was investigated using transmission electronic microscopy (TEM), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and atomic force microscopy (AFM), respectively. The results show that the contents of AlN nanoparticles increase with density of pulse current and on-duty ratio of pulse current increasing. Whereas the size of nickel grains decreases with density of pulse current increasing and on-duty ratio of pulse current decreasing. Ni–AlN composite coating consists of crystalline nickel (∼68nm) and AlN particles (∼38nm). SEM and AFM observations show that the composite coatings obtained by PED showed more compact surfaces and less grain sizes, whereas those obtained by direct current electrodepositing have rougher surfaces and bigger grain sizes.

Keywords: Composite coating; Pulse electrodeposition; Characterization; Compact surface

Microstructures of Ni–AlN composite coatings prepared by pulse electrodeposition technology by Fafeng Xia; Huibin Xu; Chao Liu; Jinwu Wang; Junjie Ding; Chunhua Ma (pp. 7-11).

Keywords: Composite coating; Pulse electrodeposition; Characterization; Compact surface

Influence of Hf doping on interfacial layers of Ta₂O₅ stacks studied by ellipsometry by Y. Karmakov; A. Paskaleva (pp. 12-18).

► Interfacial layer modifications of Hf-doped Ta₂O₅ stacks were studied by VASE. ► Constituent volume fraction depth profiles and elemental profiles were retrieved. ► Homogenization of the composition was detected for stacks with nitrided substrates. ► The assistance of HfN bonds for modifications in interfacial depth was suggested. ► Quantitative analysis of the main elemental redistributions in depth was performed.The influence of Hf doping on the interfacial layer of Ta₂O₅ stacks was studied by Variable angle spectroscopic ellipsometry (VASE). It was demonstrated new abilities of ellipsometry, beyond the traditional control of thicknesses and optical constants of very thin layers in stacks. An uncommon approach with a proper algorithm for VASE data interpretation was applied to identify the interfacial layer composition, the main interfacial constituents, the elemental depth profiles and its modification due to Hf intervention. In the investigated interfacial layers an inhomogeneous presence of non-transparent Si constituent was detected. A quantitative analysis of Si distribution in IL depth was performed. The depth profiles of other constituents as “effective” Si₃N₄, Ta₂O₅ and SiO₂ were also retrieved in stacks with nitrided and bare Si substrates. Hf doping of stacks with nitrided substrates strongly affects the interfacial homogeneity by the assistance of nitrogen presence. Moreover, scavenging of SiO₂ by Hf and IL thickness reduction were observed. In stacks on bare Si substrate the Hf doping did not produce significant changes. Some comments for the possible reactions were proposed.

Keywords: Spectroscopic ellipsometry; Algorithm; High-; k; stack; Interfacial layer; Hf-doped; Depth profile; Constituent; Homogenization

Influence of Hf doping on interfacial layers of Ta₂O₅ stacks studied by ellipsometry by Y. Karmakov; A. Paskaleva (pp. 12-18).

Keywords: Spectroscopic ellipsometry; Algorithm; High-; k; stack; Interfacial layer; Hf-doped; Depth profile; Constituent; Homogenization

The change of steel surface chemistry regarding oxygen partial pressure and dew point by Martin Norden; Marc Blumenau; Thiemo Wuttke; Klaus-Josef Peters (pp. 19-31).

► Adsorbed water at the surface is the driving force for selective oxidation. ► Effective oxygen partial pressure is dependent on the dew point. ► The dew point is the key parameter for process control for industrial application.By investigating the surface state of a Ti-IF, TiNb-IF and a MnCr-DP after several series of intercritical annealing, the impact of the annealing gas composition on the selective oxidation process is discussed. On behalf of the presented results, it can be concluded that not the general oxygen partial pressure in the annealing furnace, which is a result of the equilibrium reaction of water and hydrogen, is the main driving force for the selective oxidation process. It is shown that the amounts of adsorbed gases at the strip surface and the effective oxygen partial pressure resulting from the adsorbed gases, which is mainly dependent on the water content of the annealing furnace, is driving the selective oxidation processes occurring during intercritical annealing. Thus it is concluded, that for industrial applications the dew point must be the key parameter value for process control.

Keywords: Selective oxidation; Advanced High Strength Steels (AHSS); Continuous hot-dip galvanizing; Sub-surface; Heterogeneous gas/metal reaction

The change of steel surface chemistry regarding oxygen partial pressure and dew point by Martin Norden; Marc Blumenau; Thiemo Wuttke; Klaus-Josef Peters (pp. 19-31).

Keywords: Selective oxidation; Advanced High Strength Steels (AHSS); Continuous hot-dip galvanizing; Sub-surface; Heterogeneous gas/metal reaction

Effect of buffer layer deposition on diameter and alignment of carbon nanotubes in water-assisted chemical vapor deposition by Shashikant P. Patole; Jae-Hun Jeong; Seong Man Yu; Ha-Jin Kim; Jae-Hee Han; In-Taek Han; Ji-Beom Yoo (pp. 32-38).

The catalytic rearrangement during the CNT growth is mainly influenced by the barrier layer topography, which in turn depends on its deposition rate and thus affects the CNT diameter and alignment.Display Omitted► Deposition rate of the buffer layer governs the substrate topography. ► Buffer layer topography influences the catalyst rearrangement. ► A higher deposition rate makes the substrate rougher. ► Rougher substrate grows the aligned, small diameter CNTs with greater height. ► Slow deposition rate samples show the opposite trend.Vertically aligned carbon nanotubes (CNTs) grown by water-assisted chemical vapor deposition have revealed differences in structure and morphology depending on the deposition rate of the Al buffer layer. Rearrangement of the Fe catalyst during CNT growth is mainly influenced by the buffer layer topography, which in turn depends on the buffer layer deposition rate. A higher deposition rate makes the substrate rougher and causes the growth of more aligned, low diameter CNTs with greater height. In contrast, slow deposition results in a smooth surface, which grows misaligned, large diameter CNTs with less height. Based on the results, a CNT growth model has been proposed.

Keywords: Carbon nanotubes; Buffer layer; Catalyst; Surface topography; Growth mechanism

Enhanced photocatalytic activity of nitrogen doped TiO₂ photocatalysts sensitized by metallo Co, Ni-porphyrins by Jinfen Niu; Binghua Yao; Yuanqing Chen; Chao Peng; Xiaojiao Yu; Jian Zhang; Guanghai Bai (pp. 39-44).

► Four kinds of metalloporphyrin sensitized nitrogen-doped titanium dioxide composites have been prepared successfully. ► Four composites as photocatalysts have been investigated and contrasted for the first time. ► The mechanisms of higher degradation efficiency for cobalt porphyrins sentisized N-TiO₂ are reduced.Nitrogen doped anatase TiO₂ powders (N-TiO₂) were sensitized by four kinds of metalloporphyrins (CoTHPP, CoTPP, NiTHPP, and NiTPP). The resulting materials were characterized by XRD, TEM, XPS, DRS and N₂ adsorption. The results showed that the crystal structure and morphology of N-TiO₂ were not affected by the existence of porphyrin on its surface, but the surface area increased after the N-TiO₂ sensitized by metalloporphyrins. The photocatalytic degradation of methyl blue (MB) experiments showed that the metalporphyrins sensitized N-TiO₂ composite catalysts, especially the CoTHPP/N-TiO₂ and CoTPP/N-TiO₂, exhibited higher degradation efficiency than the unsentisized N-TiO₂ powders. In addition, the photocatalytic degradations of MB using the composite catalysts were all demonstrated to follow first-order kinetic model. The composite catalysts can be recycled four times without significant loss of photocatalytic activity.

Keywords: Metalloporphyrin; TiO; ₂; Nitrogen doping; Photocatalytic; Methylene blue

Aldoses on Ni/Pd(111) surfaces: A TPD study by Jesse R. McManus; John M. Vohs (pp. 45-51).

Display Omitted► Ni/Pd(111) bimetallic catalysts were prepared with surface and subsurface Ni layers. ► Reaction of glycolaldehyde, glyceraldehyde and glucose was characterized using TPD. ► The main reaction pathway was dehydrogenation forming CO and H₂ for all molecules. ► Activity followed the trend Pd(111). ► Pd-Ni-Pd–Ni-Pd-Pd. ► Thick Ni/Pd.The catalytic production of fuels and chemicals from biomass requires a greater understanding of the chemistry of biomass derived sugars on advanced catalyst surfaces. This study examines the reaction of cellulosic derivatived-glucose and functional surrogates glycolaldehyde and glyceraldehyde on the bimetallic Ni/Pd(111) surface using temperature programmed desorption (TPD) in ultra high vacuum (UHV). It was found that the primary reaction pathway on the Ni/Pd system for all three molecules was dehydrogenation to produce CO and H₂. Additionally, it was found that of the surfaces studied, the reforming activity followed the trend Pd(111)>Pd-Ni-Pd≈Ni-Pd-Pd>thick Ni/Pd. The Ni terminated surfaces were also found to produce ethylene at high temperatures and saw generally higher temperature and broader H₂ desorption peaks, suggesting a higher energy barrier for CH bond scission.

Keywords: Bimetallic, Ni, Pd(1; 1; 1), Glucose, Glyceraldehyde, Glycolaldehyde

Aldoses on Ni/Pd(111) surfaces: A TPD study by Jesse R. McManus; John M. Vohs (pp. 45-51).

Keywords: Bimetallic, Ni, Pd(1; 1; 1), Glucose, Glyceraldehyde, Glycolaldehyde

Microstructure, thermal shock resistance and thermal emissivity of plasma sprayed LaMAl₁₁O₁₉ (M=Mg, Fe) coatings for metallic thermal protection systems by Hong-Zhi Liu; Jia-Hu Ouyang; Zhan-Guo Liu; Ya-Ming Wang (pp. 52-59).

► LaMAl₁₁O₁₉ (M=Mg, Fe) coatings were prepared by air plasma spraying on nickel-base superalloy substrate. ► LaMAl₁₁O₁₉ coatings consist of a hexaaluminate phase with magnetoplumbite structure and an amorphous phase. ► The amorphous phase in coatings disappears and a LaAlO₃ phase is formed during thermal cycling at both 1000 and 1200°C. ► The emissivity of LaFeAl₁₁O₁₉ coating is about 0.7 at short wavelengths and above 0.9 in the wavelength range of 7–14μm.LaMAl₁₁O₁₉ (M=Mg, Fe) ceramic coatings were plasma-sprayed on nickel-based superalloy with NiCoCrAlYTa as the bond coat. The microstructure, thermal shock resistance and thermal emissivity of these two ceramic coatings were investigated. LaMAl₁₁O₁₉ coatings exhibit a characteristic of stacked lamellae, and consist mainly of a magnetoplumbite-type hexaaluminate phase and an amorphous phase. During thermal cycling, the amorphous phase disappears and a LaAlO₃ phase is formed at temperatures of both 1000 and 1200°C. The thermal cycling numbers of LaMgAl₁₁O₁₉ coating are 102 at 1000°C and 42 at 1200°C; LaFeAl₁₁O₁₉ has a thermal cycling lifetime of 87 at 1000°C and 30 at 1200°C, respectively. Normal spectral emissivity of nickel-based superalloy is about 0.2 over the whole wavelength range of 3–14μm. However, the emissivity of LaFeAl₁₁O₁₉ coating is about 0.7 at short wavelengths and above 0.9 in the wavelength range of 7–14μm.

Keywords: Coating; Hexaaluminate; Thermal shock resistance; Thermal emissivity

Association of poly( N-isopropylacrylamide) containing nucleobase multiple hydrogen bonding of adenine for DNA recognition by Hsiu-Wen Yang; Jem-Kun Chen; Chih-Chia Cheng; Shiao-Wei Kuo (pp. 60-69).

Display Omitted► Interaction between PNIPAAm and adenine is evaluated by FTIR for DNA recognition. ► Supramolecule by a nucleobase-like hydrogen bonding (NLHB) has been found firstly. ► The supramolecule generate specific surface properties and temp. responsiveness. ► K_a of the complexation is obtained to realize the formation of supramolecule.In this study we used the poly( N-isopropylacrylamide) (PNIPAAm) as a medium to generate PNIPAAm–adenine supramolecular complexes. A nucleobase-like hydrogen bonding (NLHB) between PNIPAAm and adenine was found that changed the morphology, crystalline structure, and temperature responsiveness of PNIPAAm microgels relatively to the adenine concentrations. With increasing the adenine concentration, the PNIPAAm–adenine supramolecular complexes gradually altered their morphologies from microgel particles to thin film structures and suppressed the thermodynamical coil-to-globule transition of PNIPAAm because of the NLHB existed between the PNIPAAm amide and ester groups and the adenine amide groups (CO⋯HN and NH⋯NR), verified by FTIR spectral analysis. NLHB was also diverse and extensive upon increasing the temperature; therefore, the thermoresponsive behavior of the complexes was altered with the NLBH intensity, evaluated by the inter-association equilibrium constant ( K_a) above and below their LCST. Therefore, PNIPAAm can be as a medium to recognize adenine in various concentrations, which could potentially be applied in DNA recognition.

Keywords: Supramolecule; Poly(; N; -isopropylacrylamide); Adenine; DNA recognition

Effect of the oxidation temperature on microstructure and conductivity of Zn_xN_y thin films and their conversion into p-type ZnO:N films by N.H. Erdogan; K. Kara; H. Ozdamar; R. Esen; H. Kavak (pp. 70-76).

► ZnO:N thin films have been fabricated by the oxidation of n-type Zn_xN_y films. ► Surface of the films was very smooth. ► XPS analysis confirmed the formation of ZnN bonds. ► p-type conductivity was achieved after oxidation at 450°C with well characteristics. ► XPS analysis confirmed the decrease of N content in the film after oxidation at 550°C.Transparent p-type ZnO:N thin films have been fabricated by the oxidation of n-type Zn_xN_y films. The Zn_xN_y thin films on glass substrate were deposited by pulsed filtered cathodic vacuum arc deposition using metallic zinc (99.999%) as a cathode target in pure nitrogen plasma. The properties of the films were examined after oxidation between 350 and 550°C in air atmosphere. The atomic force microscopy (AFM) analysis revealed that the surface morphology was smooth. As-deposited Zn_xN_y films were opaque and conductive ( ρ=4.36×10⁻³Ωcm, N_D=7.70×10²¹cm²/Vs) due to excess of Zn in the structure. After oxidation between 350 and 500°C, p-type ZnO:N thin films were obtained. The lowest resistivity of 44.50Ωcm with a hole concentration and Hall mobility of 2.08×10¹⁷cm⁻³ and 0.673cm²/Vs, respectively, was obtained after oxidation at 450°C. However, when the oxidation temperature reached to 550°C, the conduction type of the ZnO:N film was changed from p-type to n-type. X-ray photoemission spectroscopy (XPS) analysis confirmed the formation of ZnN bonds and substitution incorporation of oxygen for nitrogen on the surface of the film. Besides, with a further increase of oxidation temperature to 550°C, the decrease of N concentration in the sample was also confirmed by XPS analysis.

Keywords: p-type ZnO; Thin films; Filtered cathodic vacuum arc; Oxidation

Tunable surface free energies of functionalized molecular layers on Si surfaces for microfluidic immunosensor applications by Ramchander Chepyala; Siddhartha Panda (pp. 77-85).

Display Omitted► Surface free energies of different antibody layers evaluated. ► Each antibody linked via different aminosilanes on non- and nano-textured surfaces. ► Type of terminal groups, molecular orientations affected the surface free energies. ► Surface free energies: anti-BSA2.Enhanced antigen–antibody interactions in microfluidic immunosensors can be effected by tailoring the surface free energies of the antibody immobilized surfaces to obtain the appropriate fluid–wall interactions. We report a systematic study to evaluate the surface free energies from contact angle measurements, using the LWAB method, of different antibody (anti-BSA, anti-PSA, and anti-CRP) surfaces, each immobilized separately on to non- and nanotextured Si surfaces via a stack of functionalized layers including aminosilanes of which three different types were used. The apolar surface free energy components were independent of the physical modification in the non-functionalized and the intermediate hydrolyzed surfaces where as they depended on the nature of the surface and the chemical modifications in the subsequent functionalized stages. Surface free energies of the different antibodies immobilized with the shorter chain length aminosilane (APTES) on non- and nanotextured surfaces were in the order of anti-BSA2 was achieved which is reasonably significant when compared to the surface free energy window (Δ γ_s=40mJ/m²) of biofunctionalized surfaces. This fundamental understanding of the surface energetics of the biofunctionalized surfaces can be utilized in modulating the surface properties to design efficient immunosensors.

Keywords: Nanotexture; Contact angle; Antibody; Surface free energy; Sensor

Tunable surface free energies of functionalized molecular layers on Si surfaces for microfluidic immunosensor applications by Ramchander Chepyala; Siddhartha Panda (pp. 77-85).

Keywords: Nanotexture; Contact angle; Antibody; Surface free energy; Sensor

Mixed phase, sp²–sp³ bonded, and disordered few layer graphene-like nanocarbon: Synthesis and characterizations by Arvind Kumar; Sumati Patil; Anupama Joshi; Vasant Bhoraskar; Suwarna Datar; Prashant Alegaonkar (pp. 86-92).

► We have synthesized Graphene-like nanocarbon (GNC) sheets from charcoal precursor. ► Transformation of charcoal to GNC is explained on the basis of Raman spectroscopy. ► Atomic scale analysis and electronic properties of GNC is investigates by STM. ► Morphology is studied by SEM and HRTEM.We report on a method for the synthesis of Graphene-like nanocarbon (GNC) sheets. The obtained GNC contain mixed phase, sp²–sp³ bonded, and few atom layer of disordered carbon network. Initially, the mixture of soft wood charcoal (C), potassium nitrate (KNO₃), and sulfur (S) was subjected to the combustion process. The obtained ( as-synthesized) samples were intercalated (in H₂SO₄ (98%): HNO₃ (60%), 48h at 300K) and subsequently annealed at 1000°C for ∼60s. The as- synthesized, intercalated, and annealed samples were studied using number of characterization techniques. The Raman spectra (at λ=514nm) recorded for the as- synthesized samples showed five prominent peaks, namely, for amorphous–Carbon (a–C), D doublet, small G, and 2D band. The position and intensity of the recorded peaks were varied for the intercalated and annealed samples. Our SEM analysis revealed that, the area of the GNC sheets varied typically in the range of 10 to 20μm². The analysis of HRTEM/SAED together showed that the intercalated samples contained a–C phase, whereas, short range ordering was observed for the annealed samples. The tunneling spectra recorded for the annealed GNC sheets showed V-shaped local density of states with the peak present near the minima. Our analysis revealed that, the sp² chains and the polycyclic carbon rings (PCR) could be formed in the host ta–C matrix generating mixed sp²–sp³ bonded carbon network along with the local disorder. Details are presented.

Keywords: Graphene-like nanocarbon; Combustion synthesis, optical properties; High resolutions electron microscopy; Scanning probe techniques

Surface modification of 2205 duplex stainless steel by low temperature salt bath nitrocarburizing at 430°C by Runbo Huang; Jun Wang; Si Zhong; Mingxing Li; Ji Xiong; Hongyuan Fan (pp. 93-97).

2205 stainless steel was modified by salt bath nitrocarburizing at 430˚C in this study. The microstructure, surface hardness and erosion–corrosion resistance were systematically evaluated. Salt bath nitrocarburizing at 430˚C can form a nitrocarburized layer, and with the treated time prolong, the thickness of the layer increased. By nitrocarburizing within 8h, only expanded austenite (S phase) formed. With treated time increased, CrN gradually diffused from the places where there were ferrite grains in the layer before nitrocarburizing. Besides, the depth increased with the nitrocarburized time and the layer grew approximately conforms to the parabolic rate law. Salt bath nitrocarburizing can effectively improve the surface hardness of 2205 DSS. The erosion–corrosion resistance was improved by salt bath nitrocarburizing and the 16h treated sample had the best erosion–corrosion behavior.Display Omitted► S phase formed that it shows the ferrite phase dissolved in the S phase. ► CrN phase diffuses from the places where they were ferrite grains before treated. ► The hardness of the treated samples increased with good erosion–corrosion behavior.2205 stainless steel was modified by salt bath nitrocarburizing at 430°C in this study. The microstructure, surface hardness and erosion–corrosion resistance were systematically evaluated. Salt bath nitrocarburizing at 430°C can form a nitrocarburized layer, and with the treated time prolong, the thickness of the layer increased. By nitrocarburizing within 8h, only expanded austenite (S phase) formed. With treated time increased, CrN gradually diffused from the places where there were ferrite grains in the layer before nitrocarburizing. Besides, the depth increased with the nitrocarburized time and the layer grew approximately conforms to the parabolic rate law. Salt bath nitrocarburizing can effectively improve the surface hardness of 2205 DSS. The erosion–corrosion resistance was improved by salt bath nitrocarburizing and the 16h treated sample had the best erosion–corrosion behavior.

Keywords: 2205 stainless steel; Salt bath nitrocarburizing; Low temperature; Erosion–corrosion

Surface modification of 2205 duplex stainless steel by low temperature salt bath nitrocarburizing at 430°C by Runbo Huang; Jun Wang; Si Zhong; Mingxing Li; Ji Xiong; Hongyuan Fan (pp. 93-97).

Keywords: 2205 stainless steel; Salt bath nitrocarburizing; Low temperature; Erosion–corrosion

A novel and simple electrochemical sensor for electrocatalytic reduction of nitrite and oxidation of phenylhydrazine based on poly (o-anisidine) film using ionic liquid carbon paste electrode by Reza Ojani; Jahan-Bakhsh Raoof; Saeed Zamani (pp. 98-104).

► Ionic liquid based polymeric modified carbon paste electrode (IL/CPE) was prepared. ► IL into carbon paste changes morphology of poly (o-anisidine) (POA). ► IL/CPE-POA was applied for electrocatalytic oxidation of phenylhydrazine. ► IL/CPE-POA was applied for electrocatalytic reduction of nitrite.In this study, nitrite electroreduction and phenylhydrazine electrooxidation were investigated on poly(o-anisidine) formed by cyclic voltammetry at the surface of ionic liquid carbon paste electrode. The films were characterized by cyclic voltammetry and scanning electron microscopy (SEM) and were contrasted with poly(o-anisidine) prepared under identical conditions in the absence of ionic liquid in carbon paste electrode. This carbon paste modified electrode exhibits a good electrocatalytic capability (via an EC’ mechanism) for both electrooxidation and electroreduction of some important molecules. The obtained results showed that the catalytic oxidation peak currents of phenylhydrazine and catalytic reduction peak currents of nitrite at the surface of this simple (unfunctionalized) polymeric electrode were linearly dependent on their concentrations. Electrode was successfully applied for determination of nitrite and phenylhydrazine in real samples.

Keywords: Poly (o- anisidine); Nitrite; Phenylhydrazine; Modified electrode; Sensor

Visible-light photocatalytic decolorization of reactive brilliant red X-3B on Cu₂O/crosslinked-chitosan nanocomposites prepared via one step process by Chunhua Cao; Ling Xiao; Li Liu; Huayue Zhu; Chunhua Chen; Lin Gao (pp. 105-112).

► Cu₂O/crosslinked-chitosan nanocomposites were in situ prepared via one step process. ► The nanocomposites had a rough and porous chitosan surface layer. ► The chitosan layer could improve the adsorption ability of dye and molecular oxygen. ► Cu₂O/CS NCs exhibited high visible-light photocatalytic decolorization ability.Cu₂O/crosslinked-chitosan nanocomposites (Cu₂O/CS NCs) were in situ prepared via a simple one-step liquid phase precipitation–reduction process and characterized by XRD, FT-IR, SEM, TEM, BET, XPS and UV–vis/DRS. The characterization results showed that Cu₂O/CS NCs were almost similar spherical or ellipsoidal and the surface was rough and porous because Cu₂O particle was wrapped in chitosan. The chitosan layer was especially favorable for improving the adsorption ability of dye and molecular oxygen and restraining the recombination of electrons–holes pair. The visible-light photocatalytic decolorization behavior on Cu₂O/CS NCs was evaluated using reactive brilliant red X-3B (X-3B) as a model pollutant. The influences of various experimental factors on X-3B decolorization were investigated. It was found that the photocatalytic decolorization process on Cu₂O/CS NCs followed apparent pseudo-first-order kinetics model. The dye X-3B could be decolorized more efficiently in acidic media than in alkaline media. Cu₂O/CS NCs exhibited enhanced visible-light photocatalytic activity compared with other photocatalysts reported before under similar experimental conditions.

Keywords: Cuprous oxide; Chitosan; Photocatalytic decolorization; Visible light; Reactive brilliant red X-3B

Critical tuning of magnetron sputtering process parameters for optimized solar selective absorption of NiCrO_x cermet coatings on aluminium substrate by Lucie Gaouyat; Frédéric Mirabella; Olivier Deparis (pp. 113-117).

► Sputtered NiCr/NiCrO_x films as spectrally selective absorptive coatings. ► Optimization of the sputtering parameters enables nano-structured coating deposition. ► NiCrO_x Cermet composed of Ni nanoparticles and Cr₂O₃/NiO matrix.NiCrO_x ceramic–metal composites (i.e. cermets) exhibit not only oxidation and moisture resistances, which are very important for industrial applications, but also remarkable solar selective absorption properties. In order to reach the best optical performances with only one coating layer, tuning of the magnetron sputtering process parameters (O₂ flow rate, pressure and deposition time) was performed systematically. The process window turned out to be very narrow implying a critical tuning of the parameters. The optimal operating point was determined for a single layer coating of NiCrO_x on an aluminium substrate, leading to a spectrally integrated solar absorption as high as 78%. Among various material properties, the focus was put on the optical reflectance of the coating/substrate system, which was measured by UV–vis–NIR spectrophotometry. Using complex refractive index data from the literature, the theoretical reflectance spectra were calculated and found to be in good agreement with the measurements. Chemical analysis combined with scanning electronic and atomic force microscopies suggested a cermet structure consisting of metallic Ni particles and a compound matrix made of a mixture of chromium oxide, nickel oxide and nickel hydroxide.

Keywords: Magnetron sputtering deposition; Cermet material; Reflectivity modelling; UV–vis–NIR reflectivity; Composition analysis; Surface morphology

Synthesis, characterization and magnetic properties of carbon nanotubes decorated with magnetic M^IIFe₂O₄ nanoparticles by Syed Danish Ali; Syed Tajammul Hussain; Syeda Rubina Gilani (pp. 118-124).

► Magnetic carbon nanotubes were prepared by decorating with M^IIFe₂O₄ nanoparticles. ► A simple microemulsion method was first time used for synthesis of M^IIFe₂O₄/CNTs. ► Carbon nanotubes were uniformly coated with large number of magnetic nanoparticles. ► M^IIFe₂O₄/CNTs nanocomposites show ferromagnetic behavior at room temperature.In this study, a simple, efficient and reproducible microemulsion method was applied for the successful decoration of carbon nanotubes (CNTs) with magnetic M^IIFe₂O₄ (M=Co, Ni, Cu, Zn) nanoparticles. The structure, composition and morphology of the prepared nanocomposite materials were characterized using X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The magnetic properties were investigated by the vibrating sample magnetometer (VSM). The SEM results illustrated that large quantity of M^IIFe₂O₄ nanoparticles were uniformly decorated around the circumference of CNTs and the sizes of the nanoparticles ranged from 15 to 20nm. Magnetic hysteresis loop measurements revealed that all the M^IIFe₂O₄/CNTs nanocomposites displayed ferromagnetic behavior at 300K and can be manipulated using an external magnetic field. The CoFe₂O₄/CNTs nanocomposite showed maximum value of saturation magnetization which was 37.47emug⁻¹. The as prepared M^IIFe₂O₄/CNTs nanocomposites have many potential application in magnetically guided targeted drug delivery, clinical diagnosis, electrochemical biosensing, magnetic data storage and magnetic resonance imaging.

Keywords: Carbon nanotubes; M; ^II; Fe; ₂; O; ₄; Nanocomposites; Microemulsion method; Magnetic properties

Large-scale uniform Ag-NW tip array with enriched sub-10-nm gaps as SERS substrate for rapid determination of trace PCB77 by Wei Xu; Guowen Meng; Qing Huang; Xiaoye Hu; Zhulin Huang; Haibin Tang; Junxi Zhang (pp. 125-130).

► Densely arranged “hot spots” have been constructed on the silver-based SERS substrate. ► The SERS substrate demonstrated remarkable SERS sensitivity and high SERS homogeneity. ► High SERS sensitivity for R6G and PCB77 molecules have been achieved. ► The modification of substrate with β-cyclodextrin results in better sensitivity for PCB77.Ag-nanowire (Ag-NW) tip arrays with high density sub-10-nm gaps have been achieved via anodic aluminum oxide (AAO) template-assistant approach, and exhibit superior surface enhanced Raman scattering (SERS) performance. The Ag-NW tip arrays were fabricated via the following procedures. Firstly, the pore walls of the AAO were thinned to the sub-10-nm scale, and then a layer of Ag thin film was deposited on the AAO via silver mirror reaction. Subsequently, a layer of gold (Au) film was coated on the Ag film via ion-beam evaporation to serve as the electrode for the electrodeposition growth of Ag-NWs. Finally, the Ag-NW tip arrays with sub-10-nm gaps were exposed from the AAO template by physical milling and a subsequent chemical etching. The SERS activity of the as-fabricated substrate is verified by measuring the probe molecules of R6G and polychlorinated biphenyls (PCBs). To further improve the detection sensitivity for PCBs, the substrate was modified with β-cyclodextrin to increase its efficiency of capturing PCBs molecules. As a result, the as-fabricated SERS substrate can be utilized to measure trace 3,3′,4,4′-tetrachlorinated biphenyls (PCB77) with a concentration as low as 1×10⁻¹⁰M.

Keywords: Sub-10-nm; Hot spots; Surface enhanced Raman scattering; Trace determination; Polychlorinated biphenyls

Subsurface measurement of nanostructures on GaAs by electrostatic force microscopy by Fumihiko Yamada; Itaru Kamiya (pp. 131-135).

► We showed how the thickness of buried nanostructures beneath the semiconductor substrate can be measured by modified electrostatic force microscopy. ► The electrostatic force between the tip and the substrate depends on the height of individual nanoparticles. ► The electrostatic force depends strongly on the distance between the tip and the surface. ► We can estimate the thickness of the surface nanostructures from the fit curve for the experimental results.The size of surface buried oxide nanostructures are measured by electrostatic force microscopy (EFM). In contrast to atomic force microscopy that cannot probe subsurface structures and thickness, we show that EFM data include information about the thickness of individual nanostructures, consequently allowing us to determine the thickness of buried nanostructures on semiconductor substrates. We further show that this measurement can be performed simultaneously with AFM using EFM modulation spectroscopy.

Keywords: PACS; 73.20.At; 61.05.-a; 68.37.-d; 68.37.Ps; 68.43.-h; 68.47.Fg; 61.46.DfScanning probe microscopy; Electro static force microscopy; III-V semiconductor; Surface oxide

Subsurface measurement of nanostructures on GaAs by electrostatic force microscopy by Fumihiko Yamada; Itaru Kamiya (pp. 131-135).

Keywords: PACS; 73.20.At; 61.05.-a; 68.37.-d; 68.37.Ps; 68.43.-h; 68.47.Fg; 61.46.DfScanning probe microscopy; Electro static force microscopy; III-V semiconductor; Surface oxide

Size effect and enhanced photocatalytic activity of CuO sheet-like nanostructures prepared by a room temperature solution phase chemical method by Li Juan Wang; Qing Zhou; Yujie Liang; Honglong Shi; Guling Zhang; Baoshun Wang; Weiwei Zhang; Bo Lei; Wen Zhong Wang (pp. 136-140).

Display Omitted► Size effect and photocatalytic activity of CuO sheet-like nanoparticles were studied. ► UV–vis absorption spectrum of CuO nanostructures exhibits a strong size effect. ► Photocatalytic degradation of RhB of CuO sheet-like nanostructures was evaluated. ► CuO sheet-like nanostructures show 96.7% decomposition of RhB after 9h reaction. ► CuO nanostructures may have potential in catalysis and environmental remediation.Size effect and photocatalytic activity of CuO sheet-like nanostructures, which were synthesized by a facile solution phase chemical method with ethanol and water mixture as solvent, have been investigated by UV–vis absorption spectrum and photocatalytic degradation of pollutant rhodamine B (RhB). UV–vis absorption spectrum indicated that the band gap energy was about 2.31eV for the as-prepared CuO nanostructures. The result indicates that the band gap energy of the CuO sheet-like nanostructures is much larger than value of bulk CuO crystals, showing that the CuO sheet-like nanostructures exhibit a strong quantum size confinement effect. The photocatalytic activity indicates that the as-synthesized CuO sheet-like nanostructures show an enhanced photocatalytic activity with 96.7% degradation of RhB after 9h reaction under UV light irradiation, which was much higher than that of commercial CuO powders (39.6%).

Keywords: Nanostructures; Semiconductors; Photocatalytic activity; Optical property

An integrated experimental and computational approach to laser surface nitriding of Ti–6Al–4V by Sanket N. Dahotre; Hitesh D. Vora; K. Pavani; Rajarshi Banerjee (pp. 141-148).

► Computational model was developed to simulate the laser nitriding process. ► Model precisely predicts the depth of nitrogen diffusion into the Ti–6Al–4V. ► XRD, SEM and EDS analyses evidenced the formation of nitrogen rich layer ((-Ti and (-TiN). ► Length of nitrogen diffusion increased with increase in laser energy density. ► Predicted nitrogen diffusional length was successfully validated (difference ±3–4%).Titanium and its alloys have been commonly used in many biological and industrial applications owing to their excellent mechanical and physical properties. However, they have been specifically inadequate for biomedical implants due to their inferior tribological properties (low wear resistance, higher coefficient of friction, and lower hardness). As a remedy, the process of laser nitriding has emerged from the past few decades as a unique method for tailoring the surface microstructures and/or composition of titanium for enhanced tribological characteristics of titanium and its alloys. In the present study, a multiphysics computational model was developed to predict the nitrogen diffusion length into the Ti–6Al–4V alloy under various laser processing conditions (laser power and scanning speed). XRD, SEM and EDS analyses were also conducted for phase identification, microstructural investigation, and estimating the nitrogen concentration, respectively. Both computational and experimental results indicated that the depth of nitrogen diffusion increased with decrease in scanning speed, and subsequent increase in laser interaction time and increase in input laser energy density.

Keywords: Laser nitriding; Laser gas alloying; Laser surface modification; Laser surface engineering; Biomedical implants

An integrated experimental and computational approach to laser surface nitriding of Ti–6Al–4V by Sanket N. Dahotre; Hitesh D. Vora; K. Pavani; Rajarshi Banerjee (pp. 141-148).

Keywords: Laser nitriding; Laser gas alloying; Laser surface modification; Laser surface engineering; Biomedical implants

A new method for preparing bionic multi scale superhydrophobic functional surface on X70 pipeline steel by Yu Sirong; Wang Xiaolong; Wang Wei; Yao Qiang; Xu Jun; Xiong Wei (pp. 149-155).

Display Omitted► We analyzed theoretically the formation of the hydrophobic property. ► The superhydrophobic surface was obtained on X70 pipeline steel by a new method. ► The better technology parameter preparing superhydrophobic surface was obtained. ► The biggest contact angle of the sample surface with distilled water was 153.52°.The hydrophobic property of a rough surface with a low free energy coating was theoretically analyzed in this paper. In order to obtain a superhydrophobic surface, a rough surface morphology must be formed in addition to the low free energy coating on the surface. Through the shot blasting, chemical etching with concentrated hydrochloric acid, and low free energy modification with myristic acid ethanol solution, the superhydrophobic surface was obtained on X70 pipeline steel. The better process parameters for preparing superhydrophobic surface on X70 pipeline steel were obtained. The diameter of the stainless steel shot used in the shot blasting was 0.8–1.0mm. The concentration of hydrochloric acid was 6mol/L. The chemical etching time was 320min. The concentration of myristic acid ethanol solution was 0.1mol/L. The soaking time in myristic acid ethanol solution was 72h. After X70 pipeline steel surface was treated using the process parameters mentioned above, the biggest contact angle between the specimen surface and distilled water was 153.5°, and the sliding angle was less than 5°.

Keywords: Shot blasting; Bionics; Micro-nano multi-scale structure; Myristic acid; Superhydrophobicity

A new method for preparing bionic multi scale superhydrophobic functional surface on X70 pipeline steel by Yu Sirong; Wang Xiaolong; Wang Wei; Yao Qiang; Xu Jun; Xiong Wei (pp. 149-155).

Keywords: Shot blasting; Bionics; Micro-nano multi-scale structure; Myristic acid; Superhydrophobicity

Microstructural evolution during nitriding, finite element simulation and experimental assessment by S.M. Hassani-Gangaraj; M. Guagliano (pp. 156-163).

► FE simulation of nitriding is proposed, using the analogy between diffusion and conduction. ► Nitrided layer was characterized by OM, SEM observation, micro-hardness and XRD measurements. ► Diffusion zone is constituted by two different microstructures. ► Different residual stress and FWHM trends were found in the two parts of diffusion zone. ► Geometry dependency of layers growth and formation is captured by developed FE model.A finite element simulation of nitriding is proposed in this paper, using the analogy between diffusion and heat conduction, to overcome the shortcomings of the classical internal oxidation model in predicting the kinetics of layer growth and nitrogen distribution during nitriding. To verify the model, a typical gas nitriding has been carried out on an axisymmetric specimen. Treated specimen has been characterized using optical microscopy (OM), scanning electron microscopy (SEM), micro-hardness and X-Ray diffraction (XRD) measurements. It was found that the so-called diffusion zone can be divided into two parts with different influence on the mechanical characteristics including residual stress and hardening. First layer which is a two phase region of ferritic matrix and γ′ (Fe₄N) makes further improvement with respect to the second layer which is a solid solution of nitrogen in ferrite. The formation of that two phase region, which is not predicted by classical model, can be efficiently recognized by the proposed model. It is also proved that the model has the ability to consider the geometry dependency of layer growth and formation in nitriding.

Keywords: Nitriding; Finite element simulation; Microstructure; Layers growth kinetics; Nitrogen distribution; Mechanical characteristics

Microstructural evolution during nitriding, finite element simulation and experimental assessment by S.M. Hassani-Gangaraj; M. Guagliano (pp. 156-163).

Keywords: Nitriding; Finite element simulation; Microstructure; Layers growth kinetics; Nitrogen distribution; Mechanical characteristics

Humidity effect on photocatalytic activity of TiO₂ and regeneration of deactivated photocatalysts by Myung-Geun Jeong; Eun Ji Park; Hyun Ook Seo; Kwang-Dae Kim; Young Dok Kim; Dong Chan Lim (pp. 164-170).

► Photocatalytic activity of TiO₂ for toluene oxidation under various relative humidities. ► Deactivated photocatalyst can be regenerated by exposure under UV at high humidity conditions. ► The regenerated catalysts show higher CO₂ yield than the original one. ► Enhancement of total oxidation of toluene by surface OH groups.Photocatalytic decomposition of toluene was studied using commercially available TiO₂ nanocatalysts (Degussa P25) under different ranges of relative humidity (RH). The toluene removal efficiency (sum of toluene adsorption, and partial and total oxidation) decreased with increasing RH, whereas the selectivity to CO₂ in toluene oxidation enhanced. The enhancement in activity in terms of total oxidation at higher RH led to suppressing deactivation of TiO₂ with time. On the basis of the humidity effect on photocatalytic reaction, deactivated TiO₂ catalyst could recover their activity through the regeneration process consisting of exposure of the deactivated catalysts to the UV light under high RH conditions. The regenerated catalysts under high RH showed a higher total oxidation yield of toluene than that of the original catalysts due to the formation of more hydroxyl groups on TiO₂ surface during the regeneration process.

Keywords: Photocatalysis; Humidity effects; Volatile organic compounds; Oxidation

Photocatalytic activity of Cd1−_xZn_xS/K₂Ti₄O₉ for Rhodamine B degradation under visible light irradiation by Wenquan Cui; Shanshan Ma; Li Liu; Jinshan Hu; Yinghua Liang; Joanne Gamage McEvoy (pp. 171-181).

Display Omitted► Cd1−_xZn_xS was deposited on the surface of K₂Ti₄O₉ via a precipitate method. ► The deposition of Cd1−_xZn_xS greatly increases the visible light absorption for K₂Ti₄O₉. ►The composite photo-catalysts exhibited enhanced photocatalytic degradation.Cd1−_xZn_xS-sensitized K₂Ti₄O₉ composite photocatalysts (hereafter designated as Cd1−_xZn_xS/K₂Ti₄O₉) were prepared by a facile deposition–precipitation method. The samples were characterized by X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), ultraviolet–visible diffuse reﬂectance spectra (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence spectroscopy (PL). The photocatalytic activities for degradation of Rhodamine B (RhB) were investigated under visible light irradiation. The Cd_0.8Zn_0.2S particles, which were scattered on the surface of K₂Ti₄O₉, had a relatively uniform size distribution centered around approximately 50nm, and the absorption edge of K₂Ti₄O₉ was shifted to the visible light region after the deposition of Cd_0.8Zn_0.2S. The Cd_0.8Zn_0.2S crystal was found to be hexagonal and the K₂Ti₄O₉ crystal monoclinic in the composite photocatalysts. Cd_0.8Zn_0.2S/K₂Ti₄O₉ showed lower PL peak intensity than K₂Ti₄O₉. The composite photocatalyst loaded with 30wt.% Cd_0.8Zn_0.2S exhibited the highest photo-catalytic activity, and was able to degrade 95% of RhB in 180min. The photocatalytic reaction parameters, such as initial RhB concentration, photocatalyst dosage and initial solution pH were studied. The mechanism of separation of the photo-generated electrons and holes in the Cd_0.8Zn_0.2S/K₂Ti₄O₉ composite was also discussed.

Keywords: Cd; 1−; _x; Zn; _x; S; K; ₂; Ti; ₄; O; ₉; Precipitation; Photodegradation; Rhodamine B

Facile and fast fabrication of superhydrophobic surface on magnesium alloy by Zhongwei Wang; Qing Li; Zuxin She; Funan Chen; Longqin Li; Xiaoxu Zhang; Peng Zhang (pp. 182-192).

A facile and fast method for fabricating superhydrophobic surface on AZ91D magnesium alloy is reported.Display Omitted► A facile and fast method for fabricating superhydrophobic surface on AZ91D magnesium alloy is reported. ► The method could use the high and inhomogeneous magnesium alloy surface activity to gain a rough structures. ► The as-prepared superhydrophobic surface has effective anti-corrosion effect, delay-icing effect and self-cleaning effect. ► The presented method is low-cost, environmental-friendly and has great potential value in large-scale industry production.Superhydrophobic surface has many special functions and is widely investigated by researchers. Magnesium alloy is one of the lightest metal materials among the practice metals. It plays an important role in automobile, airplane and digital product for reducing devices weight. But due to the low standard potential, magnesium alloy has a high chemical activity and easily be corroded. That seriously impedes the application of magnesium alloy. In the process of fabrication a superhydrophobic surface on magnesium alloy, there are two ineluctable problems that must be solved: (1) high chemical activity and (2) the chemical activity is inhomogeneous on surface. In this study, we solved those problems by using the two characters to gain a rough surface on magnesium alloy and obtained a superhydrophobic surface after following modification process. The results show that the as-prepared superhydrophobic surface has obvious anti-corrosion effect in typically corrosive solution and naturally humid air. The delay-icing and self-cleaning effects are also investigated. The presented method is low-cost, fast and has great potential value in large-scale industry production.

Keywords: Magnesium alloy; Superhydrophobic; Etching; Corrosion; Delay-icing; Self-cleaning

Facile and fast fabrication of superhydrophobic surface on magnesium alloy by Zhongwei Wang; Qing Li; Zuxin She; Funan Chen; Longqin Li; Xiaoxu Zhang; Peng Zhang (pp. 182-192).

Keywords: Magnesium alloy; Superhydrophobic; Etching; Corrosion; Delay-icing; Self-cleaning

Facile chemical synthesis of nanoporous layered δ-MnO₂ thin film for high-performance flexible electrochemical capacitors by Yu Hu; Jun Wang; Xionghua Jiang; Yanfeng Zheng; Zhenxing Chen (pp. 193-201).

Display Omitted► The δ-MnO₂ thin films are obtained by a facile chemical bath deposition at 15°C. ► The thin films exhibit 3D porous morphology and high hydrophilicity. ► The thin films display high capacitances of 447F/g and 22.4mF/cm². ► The thin films show a good capacitance retention ratio of 83% after 1000 CV cycles. ► The thin films show excellent mechanical flexibility and electrochemical stability.Layered δ-MnO₂ thin films with a three-dimensional nanostructure are successfully fabricated on stainless steel foil substrates for flexible electrochemical capacitors by a facile and effective chemical bath deposition technology from ethanol and potassium permanganate solution at 15°C. The as-prepared thin films display nanoporous morphology and a water contact angle of 20°. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analyses reveal that the thin films are composed of δ-MnO₂. Electrochemical data demonstrate that the δ-MnO₂ thin film electrodes can deliver a high special capacitance of 447F/g at 2mV/s, and provide a good capacitance retention ratio of 87% after 1000 continuous cycles at 10mV/s in 0.5M Na₂SO₄. Compressive and tensile bending tests show that the as-prepared electrodes can steadily work over a wide range of applied curvatures between −2.5cm⁻¹ (tension) and 2.5cm⁻¹ (compression). Only a small decrease in special capacitance (0.9% at a curvature of 2.5cm⁻¹ under compressive strain, or 1.2% at a curvature of −2.5cm⁻¹ under tensile strain) is observed even after bending for 200 cycles, indicating the excellent mechanical flexibility and electrochemical stability of the δ-MnO₂ thin film electrodes.

Keywords: Layered; δ; -MnO; ₂; thin film; Chemical bath deposition; Three-dimensional nanostructure; Bending test; Flexible electrochemical capacitor

Green emission in ZnO nanostructures—Examination of the roles of oxygen and zinc vacancies by Y.H. Leung; X.Y. Chen; A.M.C. Ng; M.Y. Guo; F.Z. Liu; A.B. Djurišić; W.K. Chan; X.Q. Shi; M.A. Van Hove (pp. 202-209).

► Green emission in ZnO is strongly suppressed by hydrogen plasma. ► Different ZnO nanostructures exhibit changes in green emission after surface modification. ► Green emission likely originates from defect complexes rather than single point defects.Green defect emission is commonly observed in ZnO nanostructures. It is frequently attributed to oxygen vacancies and used to evaluate performance and study physical mechanisms in a variety of applications, such as gas sensing and photocatalysis. However, competing hypotheses have been proposed to explain green emission, which raises questions about the role of oxygen vacancies in sensing and photocatalytic processes. The major problem in correct experimental identification of defects in ZnO is the abundance of defects present, while theoretically there are problems with accurate calculation of a defect energy level in the gap. Thus, here we adopted a different approach and studied experimentally and theoretically the interaction of ZnO with different chemical substances (hydrogen and a silane-based molecule). Based on theoretical predictions and experimental results, we can conclude that green emission can likely be assigned to defect complexes, which may contain zinc vacancies.

Keywords: ZnO; Nanostructures; Photoluminescence; Green emission

Effects of electroless composite plating Ni–Cu–P on the electrochemical properties of La–Mg–Ni-based hydrogen storage alloy by Shuqin Yang; Hongping Liu; Shumin Han; Yuan Li; Wenzhuo Shen (pp. 210-215).

► Electroless composite plating Ni–Cu–P treatment was applied to La–Mg–Ni-based alloys. ► Ni–Cu–P particles deposited on the alloy surface uniformly and compactly. ► Ni–Cu–P coatings enhanced the catalytic activity of the alloy and acted as a protective layer. ► Electrochemical characteristics have been improved effectively by the Ni–Cu–P metallic layers.In order to improve the overall electrochemical performances of La–Mg–Ni-based hydrogen storage alloy, electroless composite plating Ni–Cu–P treatment was applied to La_0.88Mg_0.12Ni_2.95Mn_0.10Co_0.55Al_0.10 alloy powders. SEM observation showed that the composite treatment resulted in spherical particles more densely depositing on the alloy surface, and subsequently EDS analysis indicated that the particles should be Ni–Cu-P compounds. These particle coatings enhanced the conductivity and the catalytic activity, besides acting as a protective layer, thereby improving the electrochemical properties of the alloy. The discharge capacity of the alloy electrode noticeably increased from 338mA/g to 361mA/g. The capacity retention after 200 charge/discharge cycles and the high rate dischargeability (HRD) at 1500mA/g discharge current density of the alloy electrode increased from 76.0% and 27.7% to 84.8% and 37.0%, respectively. The superior HRD value is believed to be ascribed to the improved kinetics from the compact metallic layers on the surface.

Keywords: La–Mg–Ni-based alloys; Composite plating; Ni–Cu–P; Electrochemical kinetic characteristics

Effect of sputtering power on the properties of ZnO:Ga transparent conductive oxide films deposited by pulsed DC magnetron sputtering with a rotating cylindrical target by Kyung-Jun Ahn; Ji-Hyeon Park; Beom-Ki Shin; Woong Lee; Geun Young Yeom; Jae-Min Myoung (pp. 216-222).

► GZO films by p-DCMS with a cylindrical target were prepared at different powers. ► The film deposited at 2.0kW showed the lowest resistivity and highest mobility. ► All films fulfilled the requirements for TCO regardless of the sputtering power.Effect of sputtering power on the properties of ZnO:Ga (GZO) transparent conductive oxide (TCO) films was investigated on the films deposited by pulsed DC magnetron sputtering with a rotating cylindrical target. At lower sputtering power up to 2.0kW, the films showed flat surfaces with some pit-like structures. However, films morphology deteriorated with higher sputtering power up to 3.5kW as reflected in the rough porous surfaces. Microstructures of the films evolved into the uniformly shaped columnar grains well aligned with the c-axis with the increasing sputtering power up to 2.0kW, but further increasing the sputtering power caused the irregularity of the grain shapes and their orientations. Accordingly, the film deposited at 2.0kW showed the lowest electrical resistivity of 4.89×10⁻⁴Ωcm achieved through the highest Hall mobility of 25.9cm²V⁻¹s⁻¹. All the GZO films in this study showed the optical transmittances higher than 80%.

Keywords: Transparent conductive oxide; Ga-doped ZnO; Pulsed DC magnetron sputtering

Characterization of direct- and back-scribing laser patterning of SnO₂:F for a-Si:H PV module fabrication by D. Canteli; I. Torres; J.J. García-Ballesteros; J. Cárabe; C. Molpeceres; J.J. Gandía (pp. 223-227).

► Study of direct and induced laser removal of SnO₂:F using UV and IR ns laser sources. ► P1 grooves with good morphologic and electric properties obtained with all methods. ► Raman and EDX characterization of the structural changes in the heat affected zones. ► UV laser irradiation through the substrate is proposed as the best scribing method.In thin film photovoltaic modules, the different solar cells are interconnected monolithically during the production process, which gives a greater control over the size and output characteristics of the finished module. The interconnection is typically achieved through different laser scribing processes made at different production steps. In thin film modules built in the superstrate configuration, the first laser process is the patterning of the transparent front electrode. This paper presents results on the investigation of this first laser scribing process on fluorine-doped tin oxide deposited onto a glass substrate using nanosecond diode-pumped solid-state laser sources. Processes made with two different wavelengths (1064nm and 355nm) and executed from the film-side and from the substrate side are compared and evaluated. The quality of the scribes is assessed with confocal and scanning electron microscopy images. In addition, Raman microscopy is used to study the extension of the heat affected zones. While good quality scribes were obtained using both wavelengths and either film-side or substrate-side irradiation, only using 355nm and substrate-side scribing yielded grooves with no observable heat affected zones. It also needed the lowest values of energy per ablated volume and allowed for the highest processing speeds. As such, substrate side ablation with 355nm is proposed as the best ablation strategy.

Keywords: Laser processing; Transparent conductive oxide; Fluorine-doped tin oxide

Comparative study of interfacial reaction between superalloy substrate and glass coating with and without alumina particles incorporation by Minghui Chen; Mingli Shen; Shenglong Zhu; Fuhui Wang (pp. 228-233).

Display Omitted► Interfacial reaction between glass coating and superalloy substrate is identified. ► Gaseous products of Zn and/or Na resulted in bubbling of glass coating. ► Alumina particles addition suppresses the progressing of interfacial reaction. ► Intact alumina/glass composite coatings were prepared. ► Mechanism of alumina particles suppressing interfacial reaction was discussed.Interfacial reaction between SiO₂–Al₂O₃–ZnO–CaO based glass coating and K38G superalloy results in gaseous products of Zn and/or Na, and bubbling surface of the glassy coating. With incorporation of alumina particles, however, intact glass/alumina composite coating, which can restrict progressing of the excessive interfacial reaction, is formed on the alloy substrate. Enhanced high-temperature strength and viscosity of glass by alumina particles incorporation ensure the composite glassy coating with high stiffness and compactness which inhibits escape of Zn and/or Na gases from the interface, accounting for its suppressing effect on interfacial reaction.

Keywords: Glassy coating; Superalloy; Interface; High temperature oxidation

Electrical properties improvement of multicrystalline silicon solar cells using a combination of porous silicon and vanadium oxide treatment by L. Derbali; H. Ezzaouia (pp. 234-239).

► Passivation of multicrystalline silicon front surface and grain boundaries and improvement of the photoluminescence of the porous silicon structure. ► An efficient antireflection coating (ARC) which enhances the solar cell performances. ► The effective minority carrier lifetime have been improved noticeably after annealing deposited films.In this paper, we will report the enhancement of the conversion efficiency of multicrystalline silicon solar cells after coating the front surface with a porous silicon layer treated with vanadium oxide. The incorporation of vanadium oxide into the porous silicon (PS) structure, followed by a thermal treatment under oxygen ambient, leads to an important decrease of the surface reflectivity, a significant enhancement of the effective minority carrier lifetime ( τ_eff) and a significant enhancement of the photoluminescence (PL) of the PS structure. We Obtained a noticeable increase of ( τ_eff) from 3.11μs to 134.74μs and the surface recombination velocity ( S_eff) have decreased from 8441cms⁻¹ to 195cms⁻¹. The reflectivity spectra of obtained films, performed in the 300–1200nm wavelength range, show an important decrease of the average reflectivity from 40% to 5%. We notice a significant improvement of the internal quantum efficiency (IQE) in the used multicrystalline silicon substrates. Results are analyzed and compared to those carried out on a reference (untreated) sample. The electrical properties of the treated silicon solar cells were improved noticeably as regard to the reference (untreated) sample.

Keywords: Multicrystalline silicon; Passivation; Porous silicon; Photoluminescence; Conversion efficiency; WTC-120 lifetime tester; IQE

Electrical properties improvement of multicrystalline silicon solar cells using a combination of porous silicon and vanadium oxide treatment by L. Derbali; H. Ezzaouia (pp. 234-239).

Keywords: Multicrystalline silicon; Passivation; Porous silicon; Photoluminescence; Conversion efficiency; WTC-120 lifetime tester; IQE

Preparation of high-capacity, weak anion-exchange membranes by surface-initiated atom transfer radical polymerization of poly(glycidyl methacrylate) and subsequent derivatization with diethylamine by Xiaolei Qian; Hua Fan; Chaozhan Wang; Yinmao Wei (pp. 240-247).

► High-capacity ion-exchange membranes by ATRP and subsequent derivatization. ► The protein adsorption capacities increase with ATRP grafting time. ► The permeability of the membrane could be manipulated by ATRP grafting time. ► pH and salt effect confirmed that the adsorption of BSA followed ion-exchange mechanism.Ion-exchange membrane is of importance for the development of membrane chromatography. In this work, a high-capacity anion-exchange membrane was prepared by grafting of glycidyl methacrylate (GMA) onto the surface of regenerated cellulose (RC) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequent derivatization with diethylamine. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to characterize changes in the chemical functionality, surface topography and pore morphology of the modified membranes. The static capacity of the prepared anion-exchange membrane was evaluated with bovine serum albumin (BSA) as a model protein. The results indicated that the anion-exchange membrane which could reach a maximum capacity of 96mg/mL for static adsorption possesses a higher adsorption capacity, and the adsorption capacity increases with the polymerization time. The effect of pH and salt concentration confirmed that the adsorption of BSA followed ion-exchange mechanism. The established method would have potential application in the preparation of anion-exchange membrane.

Keywords: Cellulose membranes; Surface modification; Atom transfer radical polymerization; Anion-exchange; Protein adsorption

Incorporation effect of Y₂O₃ on the structure and optical properties of HfO₂ thin films by Xiaoying Chen; Lixin Song; Lijun You; Lili Zhao (pp. 248-252).

► HfO₂ films with five different doping ratios of Y₂O₃ were prepared on fused silica. ► Cubic YDH films were obtained at relatively low temperature of 160°C. ► Core levels of Hf 4 f and O 1 s shifted to lower energy with doping ratio increasing. ► Optical band gap ( E_g) of the films broadened gradually with doping ratio increasing. ► An inverse correlation between E_g and refractive index of films was found.HfO₂ thin films doped with different concentration of Y₂O₃ have been prepared on fused silica at substrate temperature of 160°C using electron beam evaporation technique. The influence of doping ratio on the structure and optical properties was studied in this work. Several characterization techniques including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscope (SEM), ellipsometer and spectrophotometer were used for the study of microstructure and optical properties of the films. From the results of XPS analysis, it is found that core level peak positions of Hf 4 f and O 1 s shift to lower binding energy, which was attributed to the structure change of the HfO₂ films after Y doping. The XRD and SEM results demonstrate that the concentration of Y₂O₃ affects a lot on the crystallization of Y₂O₃ doped HfO₂ (YDH) films. Cubic phase of the films appears as the doping ratio of Y₂O₃ is over 8mol% without any post annealing process. At the meantime, the optical band gap of the film is broadened with doping ratio of Y₂O₃ increasing. An inverse correlation between band gap energy ( E_g) and refractive index ( n) of the films is also found in our work.

Keywords: Y; ₂; O; ₃; doped HfO; ₂; thin film; XPS; Structure; Band gap broadening; Refractive index

Incorporation effect of Y₂O₃ on the structure and optical properties of HfO₂ thin films by Xiaoying Chen; Lixin Song; Lijun You; Lili Zhao (pp. 248-252).

Keywords: Y; ₂; O; ₃; doped HfO; ₂; thin film; XPS; Structure; Band gap broadening; Refractive index

Microstructure and wear properties of Fe–15Cr–2.5Ti–2C– xBwt.% hardfacing alloys by Dashuang Liu; Renpei Liu; Yanhong Wei; Yan Ma; Kun Zhu (pp. 253-259).

► We fabricate Fe–15Cr–2.5Ti–2Cwt.% self-shielded metal cored hardfacing alloys with different boron additions. ► As the boron content exceeds 0.99wt.%, the hardfacing alloy possesses excellent wear resistance. ► With the addition of boron, the average carbide diameter and the carbide volume fraction both increase.In this investigation an attempt was made to study the effect of boron on microstructure and wear properties of hardfacing alloys. A new type of Fe–Cr–Ti–C self-shielded metal cored wire with varying boron content were developed to fabricate the hardfacing alloys by self-shielded metal cored arc welding. Phase composition and microstructure of the as-prepared alloys were characterized by X-ray diffraction and scanning electron microscopy. Wear behavior was investigated using a ring-on-block tester. The results showed that the average diameter of M₇(C, B)₃ (M=Cr, Fe mainly) carbide increases from 9 to 20μm and carbide volume fraction (CVF) increases from 14.10 to 36.00% with the boron increasing from 0 to 1.4wt.% in the alloy. The hardness increases rapidly as boron content increases up to 0.99wt.%, and then increases more slowly. Boron improves the wear resistance of the alloys. As the boron content exceeds 0.99wt.%, the Fe–15Cr–2.5Ti–2C hardfacing alloy possesses excellent wear resistance.

Keywords: Boron; Iron base; Hard facing; Carbon volume fraction; Wear resistance

Microstructure and wear properties of Fe–15Cr–2.5Ti–2C– xBwt.% hardfacing alloys by Dashuang Liu; Renpei Liu; Yanhong Wei; Yan Ma; Kun Zhu (pp. 253-259).

Keywords: Boron; Iron base; Hard facing; Carbon volume fraction; Wear resistance

Structural and optical characterisation of undoped and chromium doped tin oxide prepared by sol–gel method by N.B. Ibrahim; M.H. Abdi; M.H. Abdullah; H. Baqiah (pp. 260-264).

► Sn1−_xCr_xO₂ ( x=0.0, 0.02, 0.04, 0.06, 0.1, 0.2) films have been successfully prepared by sol–gel method. ► All samples have semiconductor characterisation with various band gaps. ► The films’ transparency is between 80 and 99 percentages.Transparent semiconductor thin films, Cr doped SnO₂ (Sn1−_xCr_xO₂: x=0.0, 0.02, 0.04, 0.06, 0.10, 0.20) were deposited onto glass substrates by a sol–gel method. The thermal gravitational analysis showed that mass lost happened at 120°C due to evaporation of water and ethanol. X-ray diffraction analysis showed that the Cr doped SnO₂ were polycrystalline with SnO₂ phases. The crystalline sizes were in the range of 3.7–4.9nm. The optical property measured using UV-Vis spectrophotometer showed that the transparency of all samples was more than 90% and the calculated band gaps were in the range of 3.84–3.96eV which was due to the Cr dopant that increased the samples energy band gap.

Keywords: Energy gap; Cr doped SnO; ₂; Thin films; Sol–gel

Structural and optical characterisation of undoped and chromium doped tin oxide prepared by sol–gel method by N.B. Ibrahim; M.H. Abdi; M.H. Abdullah; H. Baqiah (pp. 260-264).

Keywords: Energy gap; Cr doped SnO; ₂; Thin films; Sol–gel

Preparation of graphene oxide–Ag₃PO₄ composite photocatalyst with high visible light photocatalytic activity by Yanhui Ao; Peifang Wang; Chao Wang; Jun Hou; Jin Qian (pp. 265-270).

► Graphene oxide/Ag₃PO₄ composite photocatalysts were prepared by a simple method. ► The as-prepared composite photocatalyst show high activity under visible light. ► The effect of graphene amount on the activity of the photocatalyst was investigated.Graphene oxide/Ag₃PO₄ (GO–Ag₃PO₄) composite photocatalysts were prepared by a simple precipitant method. The obtained samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity was investigated by the degradation of MB. An increase in photocatalytic activity was observed for GO–Ag₃PO₄ composite materials compared with pure Ag₃PO₄ under visible light. This improvement was attributed to the following two reasons: increased migration efficiency of photo-induced electrons and increased adsorption activity for dye molecules. A study of the effect of the amount of GO on the photocatalytic activity showed that there was an optimum amount of 10%.

Keywords: Photocatalysis; Visible light; Ag; ₃; PO; ₄; Graphene oxide; Composite

Preparation of graphene oxide–Ag₃PO₄ composite photocatalyst with high visible light photocatalytic activity by Yanhui Ao; Peifang Wang; Chao Wang; Jun Hou; Jin Qian (pp. 265-270).

Keywords: Photocatalysis; Visible light; Ag; ₃; PO; ₄; Graphene oxide; Composite

Effects of sealing treatment on corrosion resistance and degradation behavior of micro-arc oxidized magnesium alloy wires by C.L. Chu; X. Han; F. Xue; J. Bai; P.K. Chu (pp. 271-275).

► We develop three different sealing treatments for the oxidized magnesium alloy wire. ► We compare effects of three sealing treatments on corrosion resistance in SBF. ► MAO magnesium alloy wire sealed with gelatin–HA has a better corrosion resistance. ► The wire sealed with gelatin–HA exhibits reduced degradation in both SBF and SIF.The effects of three different sealing treatments on micro-arc oxidized (MAO) medical magnesium alloy wires using boiling water, zirconia sol–gel, and organic gelatin–hydroxyapatite (HA) coatings on the surface morphology, corrosion resistance, and degradation behavior in simulated body fluid (SBF) and simulated intestinal fluid (SIF) are investigated. The treatments involving boiling water or gelatin–HA coating can effectively seal the discharge channels making the surface pores less and smaller. The treatments also improve the corrosion resistance of the MAO magnesium alloy wires, especially the samples with the gelatin–HA coatings which also exhibit reduced degradation in both simulated physiological environments.

Keywords: Magnesium; Micro-arc oxidation; Sealing treatments; Corrosion resistance

Effects of sealing treatment on corrosion resistance and degradation behavior of micro-arc oxidized magnesium alloy wires by C.L. Chu; X. Han; F. Xue; J. Bai; P.K. Chu (pp. 271-275).

Keywords: Magnesium; Micro-arc oxidation; Sealing treatments; Corrosion resistance

Synthesis of C, Ag co-modified TiO₂ photocatalyst and its application in waste water purification by Hui Liu; Xiaonan Dong; Guangjun Li; Xing Su; Zhenfeng Zhu (pp. 276-283).

Display Omitted► TiO₂ were co-modified by C and Ag and applied for the photocatalytic degradation of Rh B. ► The cooperation effect between C and Ag increased the light response of TiO₂. ► Photocalytic activity of the TiO₂ was greatly enhanced due to the modification. ► The materials reveal a high photocatalytic activity than the pure and Ag–TiO₂.Monodispersed C, Ag co-modified TiO₂ microspheres were successfully synthesized through a two-step method. Firstly, monodisperse spherical TiO₂ particles were obtained via controlled hydrolysis of TBOT (tetrabutyltitanate) in ethanol. Secondly, the C, Ag co-modified TiO₂ microspheres were prepared through a simple calcination process, in which the AgNO₃ and citric acid was used as Ag and C source, respectively. The physical and chemical properties of C, Ag co-modified TiO₂ microspheres were carefully studied by using XRD, SEM, TEM, Raman, PL spectra and UV–vis diffuse reflectance spectra (DRS), while the chemical states of C and Ag were discussed via EDS (energy dispersive spectrometer) and XPS. The photocatalytic activity of the as-prepared products was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under UV and visible-light irradiation. The photocatalytic activity research shows that, with the cooperation of two modified materials, C, Ag co-modified TiO₂ microspheres exhibit enhanced photocatalytic activity both in ultraviolet and visible-light region compared with that of pure TiO₂ and single Ag modified TiO₂ microspheres.

Keywords: Key words; C; Ag co-modified TiO; ₂; microspheres; Synthesis; Photocatalysis

Synthesis of C, Ag co-modified TiO₂ photocatalyst and its application in waste water purification by Hui Liu; Xiaonan Dong; Guangjun Li; Xing Su; Zhenfeng Zhu (pp. 276-283).

Keywords: Key words; C; Ag co-modified TiO; ₂; microspheres; Synthesis; Photocatalysis

Synthesis and surface activities of a novel di-hydroxyl-sulfate-betaine-type zwitterionic gemini surfactants by Xiang F. Geng; Xing Q. Hu; Ji J. Xia; Xue C. Jia (pp. 284-290).

Display Omitted► We synthesized a novel sulfobetaine-type zwitterionic gemini surfactants. ► Their CMC values can be as low as 10⁻⁵mol/dm³. ► They can decrease the surface tension of water to 22.2mN/m. ► They preferred to adsorb at the interface to forming micelles in solution. ► The aggregates changed from vesicles to entangled fiber-like micelles as the chain length increased from 12 to 14.A series of novel di-hydroxyl-sulfate-betaine-type zwitterionic gemini surfactants of 1,2-bis[ N-ethyl- N-(2-hydroxyl-3-sulfopropyl)-alkylammonium] alkyl betaines (DBA s–_n, where s and n represent the spacer length of 2, 4 and 6 and the hydrocarbon chain length of 8, 12, 14, 16 and 18, respectively) were synthesized by reacting alkylamine with sodium 3-chloro-2-hydroxypropanesulfonate (the alternative sulphonated agent), followed by the reactions with а, ω-dibromoalkyl and then ethyl bromide. Their adsorption and aggregation properties were investigated by means of equilibrium surface tension, dynamic light-scattering (DLS) and transmission electron microscopy (TEM). DBA s–_n gemini surfactants showed excellent surface activities and packed tightly at the interface. For example, the minimum CMC value for DBA s–_n series was of the order of 10⁻⁵M and the surface tension of water can be decreased as low as 22.2mN/m. It was also found that the aggregates of DBA s–_n solutions were significantly dependent on their hydrocarbon chain lengths. The aggregates changed from vesicles to entangled fiber-like micelles as the chain length increased from dodecyl to tetradecyl.

Keywords: Adsorption; Aggregation; Betaine; Gemini surfactants; Surface tension

Synthesis and surface activities of a novel di-hydroxyl-sulfate-betaine-type zwitterionic gemini surfactants by Xiang F. Geng; Xing Q. Hu; Ji J. Xia; Xue C. Jia (pp. 284-290).

Keywords: Adsorption; Aggregation; Betaine; Gemini surfactants; Surface tension

Theoretical study of the adsorption and dissociation mechanism for methylamine on Pd(111) by Jian-Hong Liu; Cun-Qin Lv; Yong Guo; Gui-Chang Wang (pp. 291-298).

► Density functional theory is used to investigate the decomposition mechanisms. ► The energy barriers of the possible elementary reactions involved are obtained. ► CH bond scission is favored to the NH bond. ► BEP correction was found for CH/NH bond scission reactions.The decomposition mechanisms of methylamine on Pd(111) has been systematically investigated with the DFT-GGA method using the repeated slab model, and the decomposition network has been mapped out. The adsorption energies under the most stable configuration of the possible species and the energy barriers of the possible elementary reactions involved are obtained in this work. Desorption is preferable for adsorbed methylamine and hydrogen, while for the other species decomposition is preferred. Through systematic calculations for the reaction mechanism of methylamine decomposition on Pd(111), we found the most likely decomposition path is H₃CNH₂→H₂CNH₂→HCNH→HNC+HCN→CN+H₂. The decomposition products are in general agreement with the previous experimental observations.

Keywords: Methylamine; Reaction mechanism; Pd(1; 1; 1); DFT calculations; Slab model

Theoretical study of the adsorption and dissociation mechanism for methylamine on Pd(111) by Jian-Hong Liu; Cun-Qin Lv; Yong Guo; Gui-Chang Wang (pp. 291-298).

Keywords: Methylamine; Reaction mechanism; Pd(1; 1; 1); DFT calculations; Slab model

Electrodeposition of porous hydroxyapatite/calcium silicate composite coating on titanium for biomedical applications by Yong Huang; Shuguang Han; Xiaofeng Pang; Qionqion Ding; Yajing Yan (pp. 299-302).

► The HA/CS coating was formed on Ti substrate by CED for the first time. ► The surface of the HA/CS coating was a porous structure. ► The HA/CS film showed higher BS and corrosion resistance than the pure HA film. ► The HA/CS coating showed better cytocompatibility than the bared Ti and HA coating.A novel method of electrolytic porous hydroxyapatite/calcium silicate (HA/CaSiO₃) composite coating was conducted on pure titanium in a mixed solution of nano-SiO₂, Ca(NO₃)₂ and NH₄H₂PO₄. SEM observation showed that the composite layer was porous, thereby providing abundant sites for the osteoblast adhesion. XRD results showed that the composite coating was mainly composed of HA and CaSiO₃. Bond strength testing exhibited that HA-CaSiO₃/Ti had higher bond strength than HA/Ti. The HA/CaSiO₃ coating was more corrosion resistant than the HA coating based on the polarization tests. In vitro cell experiments demonstrated that both the HA and HA/CaSiO₃ coatings showed better cell response than the bared titanium. In addition, the proliferation of MC3T3-E1 osteoblast cells grown on the HA/CaSiO₃ coating were remarkably higher than those on the bared Ti and pure HA coating.

Keywords: Hydroxyapatite; Silicate; Medical implants; Clinical applications; Cytocompatibility

Adhesion improvement of electroless copper plating on phenolic resin matrix composite through a tin-free sensitization process by Yong Wang; Cheng Bian; Xinli Jing (pp. 303-310).

► A tin-free sensitization process for electroless copper plating was developed. ► Discussed the reactions of phenolic resin possibly occurred during the etching process. ► Glucose used as sensitizer can improve the adhesion of copper plating. ► The adhesion improvement was attributed to the anchor effect of concave holes. ► The distribution of catalyst particles affected the properties of plating.In order to improve the adhesion of electroless copper plating on phenolic resin matrix composite (PRMC), a new and efficient tin-free sensitization process has been developed. Electroless copper plating could be achieved in three steps, namely: (i) chemical etching with potassium permanganate solution; (ii) sensitization and activation with glucose and silver nitrate solution respectively; and (iii) electroless copper plating. Compared with the sample sensitized with stannous chloride (SnCl₂), the copper plating obtained in the tin-free process showed excellent adhesion with the PRMC substrate, but had lower plating rate and conductivity. Additionally, the morphology of the copper plating was affected by the sensitization process, and the tin-free process was conducive to the formation of the large spherical copper polycrystal. Although the process is slightly complicated, the new sensitization process is so low-cost and environment-friendly that it is of great significance and could be applied into large-scale commercial manufacturing.

Keywords: Phenolic resin matrix composite; Electroless copper plating; Sensitization; Adhesion

Adhesion improvement of electroless copper plating on phenolic resin matrix composite through a tin-free sensitization process by Yong Wang; Cheng Bian; Xinli Jing (pp. 303-310).

Keywords: Phenolic resin matrix composite; Electroless copper plating; Sensitization; Adhesion

The effect of silicon on the oxidation behavior of NiAlHf coating system by Pengchao Dai; Qiong Wu; Yue Ma; Shusuo Li; Shengkai Gong (pp. 311-316).

► The addition of Si in NiAlHf coating could contribute to the transformation from θ-Al₂O₃ to α-Al₂O₃, when oxidized at 1423K. ► After thermal exposure, the Si additions could retard the inter-diffusion of refractory elements, especially Mo and Re, between coating and substrate. ► It is of benefit to the oxidation resistance of NiAlHf coating, when the Si is dope.Two types of NiAlHf coatings doped with different content of Si (1at.% and 2at.%) were deposited on a Ni₃Al based single crystal superalloy IC32 by electron beam physical vapor deposition (EB-PVD) method, respectively. For comparison, NiAlHf coating with 0at.% Si was also prepared. The oxidation tests were carried out at 1423K in air. At the initial stage of oxidation, large amount of flake-like θ-Al₂O₃ was found on NiAlHf coating surface. However, no θ-Al₂O₃ was observed in 2at.% Si doped NiAlHf coating except α-Al₂O₃. It revealed that the Si additions could contribute to the transformation from θ-Al₂O₃ to α-Al₂O₃. When oxidation time prolonged to 100h, it was found that the degradation of NiAlHf coating was very severe with no residual β-phase, which was due to the serious inter-diffusion between the coating and substrate. In contrast, the inter-diffusion in Si-doped coating was reduced with some residual β-phase and R-Ni(Mo, Re) precipitates. The presence of Si could retard the inter-diffusion of elements between coating and substrate, indicating a barrier diffusion effect. As a result, the oxidation resistance of NiAlHf coating was improved significantly.

Keywords: NiAlHf; Oxidation; θ-Al; ₂; O; ₃; Barrier diffusion; R-Ni(Mo,Re) phase

The effect of silicon on the oxidation behavior of NiAlHf coating system by Pengchao Dai; Qiong Wu; Yue Ma; Shusuo Li; Shengkai Gong (pp. 311-316).

Keywords: NiAlHf; Oxidation; θ-Al; ₂; O; ₃; Barrier diffusion; R-Ni(Mo,Re) phase

Atomic force microscopy and tribology study of the adsorption of alcohols on diamond-like carbon coatings and steel by M. Kalin; R. Simič (pp. 317-328).

► Using AFM and tribotests we studied adsorption of hexadecanol on DLC and steel. ► Alcohols adsorb chemically and physically onto DLC and act as lubrication agents. ► Adsorption of alcohols on DLC reduces wear of the DLC coatings. ► Good correlation between AFM adsorption and tribological results was found. ► Proposed mechanisms include environmental, temperature and rubbing effects.Polar molecules are known to affect the friction and wear of steel contacts via adsorption onto the surface, which represents one of the fundamental boundary-lubrication mechanisms. Since the basic chemical and physical effects of polar molecules on diamond-like carbon (DLC) coatings have been investigated only very rarely, it is important to find out whether such molecules have a similar effect on DLC coatings as they do on steel. In our study the adsorption of hexadecanol in various concentrations (2–20mmol/l) on DLC was studied under static conditions using an atomic force microscope (AFM). The amount of surface coverage, the size and the density of the adsorbed islands of alcohol molecules were analyzed. Tribological tests were also performed to correlate the wear and friction behaviours with the adsorption of molecules on the surface. In this case, steel surfaces served as a reference. The AFM was successfully used to analyze the adsorption ability of polar molecules onto the DLC surfaces and a good correlation between the AFM results and the tribological behaviour of the DLC and the steel was found. We confirmed that alcohols can adsorb physically and chemically onto the DLC surfaces and are, therefore, potential boundary-lubrication agents for the DLC coatings. The adsorption of alcohol onto the DLC surfaces reduces the wear of the coatings, but it is less effective in reducing the friction because of the already inherently low-friction properties of DLC. Tentative adsorption mechanisms that include the environmental species effect, the temperature effect and the tribological rubbing effect are proposed for DLC and steel surfaces.

Keywords: DLC; AFM; Alcohol; Adsorption; Tribology

Atomic force microscopy and tribology study of the adsorption of alcohols on diamond-like carbon coatings and steel by M. Kalin; R. Simič (pp. 317-328).

Keywords: DLC; AFM; Alcohol; Adsorption; Tribology

Effect of thermal fatigue on the wear resistance of graphite cast iron with bionic units processed by laser cladding WC by Zhengjun Jing; Hong Zhou; Peng Zhang; Chuanwei Wang; Chao Meng; Dalong Cong (pp. 329-336).

► Effect of thermal fatigue on wear resistance of CGI was investigated. ► With the increase of thermal fatigue cycles times, obvious breaking phenomenon was found. ►. After different thermal fatigue cycles times, hardness and mass losses of samples were compared. ► Hardness and mass losses of samples with different WC content were studied.Thermal fatigue and wear exist simultaneously during the service life of brake discs. Previous researchers only studied thermal fatigue resistance or abrasion resistance of compact graphite cast iron (CGI), rather than combining them together. In this paper, wear resistance after thermal fatigue of CGI was investigated basing on the principle of bionics, which was close to actual service condition of the brake discs. In the meanwhile, the effect of thermal fatigue on wear resistance was also discussed. Non-smooth bionic units were fabricated by laser cladding WC powder with different proportions (50wt.%, 60wt.%, 70wt.%). Microstructure and microhardness of the units were investigated, and wear mass losses of the samples were also compared. The results indicate that thermal fatigue has a negative effect on the wear resistance. After the same thermal fatigue cycles times, the wear resistance of laser cladding WC samples is superior to that of laser remelting ones and their wear resistance enhances with the increase of WC content.

Keywords: Cast iron; Thermal fatigue; Wear resistance; Laser cladding

Non-isothermal oxidation of aluminum nanopowder coated by hydrocarbons and fluorohydrocarbons by A. Sossi; E. Duranti; C. Paravan; L.T. DeLuca; A.B. Vorozhtsov; A.A. Gromov; Yu. I. Pautova; M.I. Lerner; N.G. Rodkevich (pp. 337-343).

► Hydrocarbons and fluorohydrocarbons have been applied on the surface of aluminum nanopowder and comprehensively tested. ► Non-isothermal oxidation of coated aluminum nanopowder was studied by DSC-TGA. ► Fatty acids coating have a weak effect on the thermal behavior of aluminum nanopowder. ► The oxidation onset for fluoroelastomer-coated aluminum nanopowder shifts to higher temperatures by ∼20°C.Aluminum nanopowder ( nAl) obtained by electrical explosion of wires and passivated/coated with hydrocarbons and fluorohydrocarbons is comprehensively characterized. Coatings of different natures (octadecanoic and hexadecanoic acid, (1,1,11) trihydroperfluoro-undecan-1-ol, Fluorel™+ester from esterification of (1,1,11) trihydroperfluoro-undecan-1-ol with furan-2,5-dione) were applied on the particle surface. The powders were studied by TEM, SEM, DSC-TGA, and BET specific surface area. The active aluminum content was determined by volumetric analyses. Coated nAl particles were compared to non-coated powder by the corresponding reactivity parameters obtained from DSC-TGA. It was found that while fatty acids have a weak effect on the non-isothermal oxidation behavior, fluoroelastomers shift the oxidation onset of nAl to higher temperatures by ∼20°C for the first oxidation stage and by ∼100°C for the second oxidation stage.

Keywords: Aluminum nanopowder; Passivation; Coating; Oxidation; Surface structure

Perfluorinated poly(dimethylsiloxane) via the covalent attachment of perfluoroalkylsilanes on the oxidized surface: Effects on zeta-potential values by Peiling Sun; J. Hugh Horton (pp. 344-351).

Display Omitted► Poly(dimethylsiloxane) is surface-modified with perfluorinated siloxanes. ► Surfaces show increases in zeta potential with increasing perfluoroalkyl chain length. ► Perfluorinated surfaces support electro-osmotic flow across a wide pH range. ► Perfluorinated surfaces are resistant to the diffusion of PDMS oligomers.Poly(dimethylsiloxane) (PDMS) is a widely-used polymer in microfluidic devices due to its range of physical and chemical properties suitable for molding micron-sized features. However, its hydrophobicity also leads to some limitations: it poorly supports electro-osmotic flow, and can be incompatible with biomolecules and with many organic solvents. Surface modification is commonly used to vary PDMS surface properties to make it more suitable for specific microfluidic applications. Here, we report on the surface modification of PDMS using perfluoroalkane–triethoxysilanes, via the covalent attachment of triethoxysilane groups on plasma-oxidized PDMS. A device constructed from such fluorinated materials could be used for separating fluorous-tagged proteins or peptides. Modified PDMS were characterized using a range of surface analytical methods. In particular, zeta- (ζ-) potential values at the interfaces of both modified and unmodified PDMS and under varying pH conditions were measured, as ζ-potential is an essential parameter to support electroosmotic flow (EOF), a common pumping method in microfluidic devices. The results showed the length of fluorinated alkane chain has significant effect on the density of surface modifying species and topography following modification. In addition, the perfluorinated modification increases the magnitude of the ζ-potential at the PDMS interface when compared to that of native PDMS, increasing the electro-osmotic flow rate, over a wide pH range. The modified surface is resistant to the diffusion of PDMS oligomers that affects other PDMS surface modification processes.

Keywords: Poly(dimethylsiloxane); Perfluorinated alkanes; Zeta potential; Surface modification

Perfluorinated poly(dimethylsiloxane) via the covalent attachment of perfluoroalkylsilanes on the oxidized surface: Effects on zeta-potential values by Peiling Sun; J. Hugh Horton (pp. 344-351).

Keywords: Poly(dimethylsiloxane); Perfluorinated alkanes; Zeta potential; Surface modification

Assistance of partially reduced MoO₃ interlayer to hole-injection at iron phthalocyanine/ITO interface evidenced by photoemission study by L.Y. Liu; L. Wan; L. Cao; Y.Y. Han; W.H. Zhang; T.X. Chen; P.P. Guo; K. Wang; F.Q. Xu (pp. 352-356).

► Pronounced gap states were yielded in partially reduced MoO₃ (MoO_x) interlayer. ► A barrier of 0.45eV was derived for electron extraction from FePc to MoO_x smaller than to MoO₃. ► The energy level alignment diagrams were obtained for the FePc/MoO₃ and FePc/MoO_x interfaces. ► The nominal thickness was optimized to be 3nm for MoO₃ interlayer.Molybdenum trioxide (MoO₃) has been widely used as an interlayer between electrode and functional organic layer inducing significant improvement in the performance of organic electronic and optoelectronic devices such as organic light-emitting diodes (OLEDs) and organic photovoltaics (OPVs). In this work, the electronic structures and energy level alignment at FePc/MoO₃ (3nm)/ITO and FePc/MoO_x (3nm)/ITO ( x<3) interfaces have been comparatively investigated in situ by means of photoemission spectroscopy (PES) in an attempt to understand the influence of MoO_x layer on the interfacial hole injection property. It is found that the electron injection barrier is only 0.45eV for electron extraction from the highest occupied molecular orbital (HOMO) of FePc to the conduction band of MoO_x. Simultaneously, two gap states at binding energy of 1.15eV and 2.30eV present in 3nm MoO_x, which extend from the valence band maximum of MoO_x to the Fermi level. These gap states are suggested to originate from the partial occupation of Mo 4d states due to the reduction of MoO₃ during the annealing process. Both lowered electron extraction barrier and presence of interfacial gap states appear to assist the hole injection from ITO anode into FePc by the insertion of MoO_x layer.

Keywords: Iron phthalocyanine; Molybdenum oxide; Interface; Hole injection; Photoemission

Low-temperature synthesis of anatase C-N-TiO₂ photocatalyst with enhanced visible-light-induced photocatalytic activity by Deyong Wu; Lianzhi Wang (pp. 357-361).

Display Omitted► Low-temperature synthesis of anatase C-N-TiO₂ photocatalyst. ► High visible-light-induced activity. ► The existence of retained alkoxyl groups on the anatase surface. ► The synergistic effect between the TiO₂ surface complexes and nitrogen doping.Visible-light-activated C-N-TiO₂ powders were synthesized by a facile peptization-reflux method at 120°C. The physical and photophysical properties of the photocatalyst have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and UV–vis diffuse reflectance spectra. The as-prepared C-N-TiO₂ possessed a diameter of ca. 7nm with anatase crystalline structure, and showed a shift of the absorption edge to a lower energy and a stronger absorption in the visible region. XPS results indicated that the retained alkoxyl groups existed on the surface of TiO₂ and the doped nitrogen incorporated in the TiO₂ as formation of N-Ti-O and Ti-O-N. And C-N-TiO₂ samples had excellent photocatalytic activity for methyl orange degradation under visible light irradiation, which could be assigned to synergistic effect between the retained alkoxyls and the nitrogen doping.

Keywords: Titanium dioxide; Nitrogen doping; Alkoxyl groups; Low temperature; Visible light

Low-temperature synthesis of anatase C-N-TiO₂ photocatalyst with enhanced visible-light-induced photocatalytic activity by Deyong Wu; Lianzhi Wang (pp. 357-361).

Keywords: Titanium dioxide; Nitrogen doping; Alkoxyl groups; Low temperature; Visible light

Properties of Ba-hexaferrite thin films with different thicknesses by Zhiyong Xu; Zhongwen Lan; Ke Sun; Rongdi Guo; Zhong Yu; Xiaona Jiang; Guangwei Zhu (pp. 362-368).

► Effects of thickness on morphologies, textures and magnetic properties were studied. ► Thinner BaM film favors to obtain better (00 l) planes oriented and narrower XRD FWHM. ► Increasing thickness deteriorates the texture and perpendicular magnetic anisotropy.M-type Ba-hexaferrite (BaM) thin films with different thicknesses were deposited on (001) Al₂O₃ substrates by RF magnetron sputtering. Effects of film thickness on the crystallographic, morphological and magnetic properties were investigated. Experimental results showed that properties of BaM thin films are strongly dependent on thickness and thinner film favors to obtain better (00 l) planes orientation with narrower XRD FWHM. The 150-nm thick film possesses columnar-type grains having c-axis orientation perpendicular to the film plane. However, with the thickness increasing from 150 to 550nm, acicular-type grain increases. Thus, the texture of (00 l) planes orientation of the film deteriorates; the saturation magnetization and perpendicular magnetocrystalline anisotropy also decrease gradually. Mechanisms for these variations are attributed to the increase of random nucleation sites and strain relaxation in the films with increasing thickness.

Keywords: BaM thin films; Surface morphologies; Magnetic properties; Film thickness

Properties of Ba-hexaferrite thin films with different thicknesses by Zhiyong Xu; Zhongwen Lan; Ke Sun; Rongdi Guo; Zhong Yu; Xiaona Jiang; Guangwei Zhu (pp. 362-368).

Keywords: BaM thin films; Surface morphologies; Magnetic properties; Film thickness

Anti-wetting Cu/Cr coating with micro-posts array structure fabricated by electrochemical approaches by Yufeng Zhou; Tao Hang; Feng Li; Ming Li (pp. 369-372).

Display Omitted► Cu/Cr microposts structured surface was obtained simple electrochemical approaches. ► The multilayer coating with this unique structure exhibits good anti-wetting property. ► The hemispherical top of the micro-post favors the hydrophobicity of the coating. ► The wetting modes of two different microstructures are different but convertible.Microposts structured Cu/Cr multilayer coating was prepared by a simple two-step approach combining electroless and electro deposition. Surface morphologies of the as-prepared Cu/Cr multilayer coating characterized by field emission scanning electron microscopy show that this multilayer coating exhibits micro-posts arrayed structure with a layer of Cr uniformly covering the circular conical surface of Cu micro-cones array. The wettability test shows that the contact angle of Cu/Cr multilayer surface with water drop can be greater than 140° by optimizing the electrodeposition time of Cr. The mechanism of hydrophobicity of both the micro-cones arrayed and micro-posts arrayed structures was briefly discussed by comparing two different wetting modes. Due to its good anti-wetting property and unique structure, the micro-posts arrayed Cu/Cr multilayer coating is expected for extensive practical applications.

Keywords: Microstructure; Hydrophobicity; Multilayer structure; Electrodeposition

Anti-wetting Cu/Cr coating with micro-posts array structure fabricated by electrochemical approaches by Yufeng Zhou; Tao Hang; Feng Li; Ming Li (pp. 369-372).

Keywords: Microstructure; Hydrophobicity; Multilayer structure; Electrodeposition

Thermal fatigue resistance of H13 steel treated by selective laser surface melting and CrNi alloying by Xin Tong; Ming-jiang Dai; Zhi-hui Zhang (pp. 373-380).

► Selective CO₂ laser surface melting and alloying technologies were adopted. ► Thermal fatigue resistance of H13 steel is improved. ► Thermal fatigue resistance would be enhanced remarkably by laser alloying with 75%Cr25%Ni mixed powder. ► Laser alloyed zone has excellent properties such as resisting crack initiation and oxidation corrosion. ► Cracks and oxidation corrosions are restricted within narrow limits structured by laser scanning tracks.In this study, the selective laser surface melting and laser surface alloying technologies were adopted to improve the thermal fatigue resistance of medium carbon hot-work die steel (H13) by a CO₂ laser. Two kinds of mixed chromium (Cr) and nickel (Ni) powders were used as the laser alloying materials, and the effects of the mixing ratio on the thermal fatigue resistance were investigated thoroughly. Some important results such as cross-sectional morphology, phases, hardness and thermal fatigue behavior were analyzed and evaluated. It indicates that the laser surface alloying technique using mixed powder with ratio of 75%Cr–25%Ni can considerably enhance the thermal fatigue resistance of the H13 steel. The laser alloyed zone has excellent properties such as preventing crack initiation and oxidation corrosion compared with original H13. Thermal cracking and oxidation corrosion that occurred at substrate surface can be surrounded and intercepted by a gridded laser strengthened structure. Therefore, the naturally developed cracks could be effectively prevented. Theses results and analysis show that laser surface technique can be positively used to improve surface mechanical properties of H13 dies.

Keywords: Thermal fatigue; Laser surface alloying; Laser surface melting

Thermal fatigue resistance of H13 steel treated by selective laser surface melting and CrNi alloying by Xin Tong; Ming-jiang Dai; Zhi-hui Zhang (pp. 373-380).

Keywords: Thermal fatigue; Laser surface alloying; Laser surface melting

Interlayer formation of diamond-like carbon coatings on industrial polyethylene: Thickness dependent surface characterization by SEM, AFM and NEXAFS by Christian B. Fischer; Magdalena Rohrbeck; Stefan Wehner; Matthias Richter; Dieter Schmeißer (pp. 381-389).

Display Omitted► Interaction of plasma generated carbon with polyethylene material is examined. ► A model for the coating of soft plastic material with hard DLC is presented. ► Interlayer formation between these unequal materials is proven. ► The formation mechanism and thickness depend on the DLC type. ► The interlayer develops during the coating process.The coating of materials with diamond-like carbon (DLC) is a very common way to change and improve their basic characteristics. Although DLC is used on several substrates, the chemical and physical properties throughout the coating process on plastics are yet sparsely investigated. Two types of protective coatings one sp³-enriched (robust, r-type) and one with more sp²-centers (flexible, f-type) have been realized on polyethylene by PECVD deposition. SEM and AFM analysis of coated samples of DLC types revealed diverse surface topographies on different scales and images appeared even differently smoothed by the carbonaceous deposits. Grains of both DLC types are platelet-shaped and nearly double in size for the robust type indicating fundamental differences in the epitaxial DLC growth. NEXAFS spectroscopy showed significant details of carbon centers in chemically different neighborhood displaying a characteristic fingerprint behavior. Comparison of deposition models revealed a mechanism of interlayer formation which is discussed in detail. Interlayer formation is clearly the appropriate explanation of the process for the current carbon deposition between these two unequal materials. An improved understanding of hard DLC and soft polyethylene assembly is given in the presented work.

Keywords: Diamond-like carbon; Interlayer formation; Polyethylene; Surface characterization; Coatings; Plastics

Graded/soft/graded exchange-coupled thin films fabricated by [FePt/C]₅/Fe/[C/FePt]₅ multilayer deposition and post-annealing by Fang Wang; Jing Zhang; Jun Zhang; Chunling Wang; Zhenfeng Wang; Hao Zeng; Mingang Zhang; Xiaohong Xu (pp. 390-393).

Display Omitted► A novel exchange-coupled graded/soft/graded film is developed and then fabricated. ► Large reduction in coercivity is obtained in the graded/soft/graded film. ► Adding C layers can tailor the anisotropy gradient and refine the grain size. ► Magnetization reversal mechanism is revealed by micromagnetic simulations.We report the fabrication of exchange-coupled graded/soft/graded films with well-isolated magnetic grains. In contrast to the FePt/Fe exchange spring film, a reduction of up to 72% in coercivity value in the graded/soft/graded film can be obtained. Adding C layers with different thicknesses not only tailors the anisotropy gradient, but also refines the grain size and weakens the intergranular exchange interactions. Micromagnetic simulations reveal that the magnetization reversal proceeds by the propagation of a partial domain wall into the hard FePt layers from the center of the soft Fe layer. The formation of partial domain wall can assist the two graded FePt layers to switch simultaneously, resulting in a lower coercivity.

Keywords: Sputtering; Thin films; Graded media; L; 1; ₀; –FePt; Exchange-coupled

Structural morphology study of Cd²⁺ induced Langmuir Blodgett multilayer films of arachidic acid by Dhrubojyoti Roy; Nayan Mani Das; P.S. Gupta (pp. 394-401).

► Well defined pattern deposition of CdAA molecules with uniform packing. ► Tilting occurs in long chain fatty acids synthesized by LB method. ► Pinhole defects presence was seen minimal upto 21st monolayer in LB prepared CdAA fatty acid films at pH ∼6.8. ► FTIR and XPS study indicates the formation of unidentate bridging metal-carboxylate coordination.The organization and headgroup co-ordination of Cadmium Arachidate (CdAA) molecule in Langmuir–Blodgett (LB) multilayer films deposited on hydrophilic Glass (SiO₂) and Silicon (100) substrate at normal subphase pH (6.8) are studied. X-ray diffraction (XRD) and X-ray reflectivity (XRR) study reveals ordered layer by layer organization with uniform packing of CdAA molecules, and with a small tilt angle of alkyl chain of CdAA molecule equal to 6.8°±1.75°. Electron density profiles (EDPs) shows that the coverage of films remains almost constant with increase in bilayer thickness which indicate very little presence of pinhole defects. AFM study for 25 ML shows that coverage of the film remain intact upto 22nd ML and then decreases sharply due to presence of pinhole defects. Fourier transform infrared spectroscopy (FTIR) study is also consistent with XRD and XRR study of ordered deposition of CdAA molecule. FTIR and X-ray photoelectron spectroscopy (XPS) study indicates the formation of unidentate bridging metal-carboxylate coordination type headgroups consistent with one cadmium metal ion between two carboxylate (COO) groups in each headgroup structure.

Keywords: LB film; CdAA monolayer; Layered crystalline growth; Alkyl chain tilt; Unidentate headgroup coordination

Structural morphology study of Cd²⁺ induced Langmuir Blodgett multilayer films of arachidic acid by Dhrubojyoti Roy; Nayan Mani Das; P.S. Gupta (pp. 394-401).

Keywords: LB film; CdAA monolayer; Layered crystalline growth; Alkyl chain tilt; Unidentate headgroup coordination

Antireflective nanostructures fabricated by reactive ion etching method on pyramid-structured silicon surface by Zhihao Yue; Honglie Shen; Ye Jiang (pp. 402-406).

► A low reflectance of 4.72% was obtained by etching the pyramid-structured silicon wafers in a RIE system. ► The whole etching process was at room temperature and without any negative voltage pulses. ► Samples etched with F_O2 lower than 6sccm can’t get low reflective silicon structure. ► Too big etching power of 225W would make the nanostructures too sparse to obtain a low reflectance.In this paper, pyramid-structured silicon wafers were etched in a reactive ion etching system at room temperature and without any negative voltage pulses to obtain antireflective nanostructures. The effects of the etching time, etching power and the flow ratio of the SF₆ and O₂ (F_SF6/F_O2) on the morphologies and reflective properties of the etched samples were studied. Scanning electron microscope was used to investigate the morphologies of etched samples. The surface reflectance measurements were carried out using UV–vis-NIR spectrophotometer. A reflectance of 4.72% from the etched surface in the wavelength range of 400–800nm was obtained under etching time of 20min, etching power of 150W and F_SF6/F_O2 of 18sccm/6sccm. Meanwhile, samples etched with F_O2 lower than 6sccm can’t get low reflective silicon structure. Besides, the results show that overlong etching time of 30min and too big etching power of 225W would make the nanostructures too sparse to obtain a low reflectance.

Keywords: Reactive ion etching; Antireflective nanostructure; Pyramid; Etching time; Etching power; F; _SF6; /F; _O2

Antireflective nanostructures fabricated by reactive ion etching method on pyramid-structured silicon surface by Zhihao Yue; Honglie Shen; Ye Jiang (pp. 402-406).

Keywords: Reactive ion etching; Antireflective nanostructure; Pyramid; Etching time; Etching power; F; _SF6; /F; _O2

A study of copper oxide based resistive switching memory by conductive atom force microscope by Qianfei Zhou; Qian Lu; Xin Zhang; Yali Song; Yin Yin Lin; Xiaojing Wu (pp. 407-411).

► CuO film was fabricated by plasma oxidation method. ► Film structure property was characterized by XRD analysis. ► The resistive switching property of Pt/Cu_xO/Cu was studied by C-AFM and DC sweeping. ► O vacancies conductive filament is the mechanism for Pt/Cu_xO/Cu switching properties. ► The random formation/rupture of conductive filaments causes the instability of HRS.A copper oxide (Cu_xO) layer was formed by applying plasma oxidization on a copper film grown on a Si substrate. Pt deposited on this Cu_xO layer then function as the top electrode to form a Pt/Cu_xO/Cu structure. A device created with this structure exhibited a forming-free bipolar resistive switching property. Conductive atom force microscope (C-AFM) was employed to investigate the nanoscale electrical properties of the device. Based on I– V curve analysis, it was found that the Poole–Frankel and conducting filaments models were suitable for the present device. C-AFM analysis for the sample indicated that the random formation/rupture of conducting paths in the Cu_xO layer may play a key role for the device instability in high resistance state.

Keywords: Copper oxide; Resistive switching; Conductive atom force microscope

A study of copper oxide based resistive switching memory by conductive atom force microscope by Qianfei Zhou; Qian Lu; Xin Zhang; Yali Song; Yin Yin Lin; Xiaojing Wu (pp. 407-411).

Keywords: Copper oxide; Resistive switching; Conductive atom force microscope

Surface functionalization of 3D glass–ceramic porous scaffolds for enhanced mineralization in vitro by Sara Ferraris; Chiara Vitale-Brovarone; Oana Bretcanu; Clara Cassinelli; Enrica Vernè (pp. 412-420).

► 3D macroporous glass–ceramic scaffolds obtained by the sponge replication method. ► Scaffolds present excellent mechanical properties and moderate bioactivity. ► Scaffolds have been surface functionalized by the alkaline phosphatase enzyme (ALP). ► ALP maintains its activity after grafting. ► ALP improves and quickens hydroxyapatite precipitation on scaffold surface.Bone reconstruction after tissue loosening due to traumatic, pathological or surgical causes is in increasing demand. 3D scaffolds are a widely studied solution for supporting new bone growth. Bioactive glass–ceramic porous materials can offer a three-dimensional structure that is able to chemically bond to bone. The ability to surface modify these devices by grafting biologically active molecules represents a challenge, with the aim of stimulating physiological bone regeneration with both inorganic and organic signals. In this research work glass ceramic scaffolds with very high mechanical properties and moderate bioactivity have been functionalized with the enzyme alkaline phosphatase (ALP). The material surface was activated in order to expose hydroxyl groups. The activated surface was further grafted with ALP both via silanization and also via direct grafting to the surface active hydroxyl groups.Enzymatic activity of grafted samples were measured by means of UV–vis spectroscopy before and after ultrasonic washing in TRIS–HCl buffer solution. In vitro inorganic bioactivity was investigated by soaking the scaffolds after the different steps of functionalization in a simulated body fluid (SBF). SEM observations allowed the monitoring of the scaffold morphology and surface chemical composition after soaking in SBF. The presence of ALP enhanced the in vitro inorganic bioactivity of the tested material.

Keywords: Surface functionalization; Scaffold; Bone integration; Bioactivity

Enhanced room temperature ferromagnetism in hydrogenated Zn_0.98Mn_0.02O by Hua Zhang; Sai Qin; Yanqiang Cao; Zaixing Yang; Lifang Si; Wei Zhong; Di Wu; Mingxiang Xu; Qingyu Xu (pp. 421-423).

► Enhanced ferromagnetism was observed in hydrogenated Zn_0.98Mn_0.02O. ► Hydrogenation facilitates the substitution of the interstitial Mn ions on Zn sites. ► The ferromagnetic mediation by the interstitial H has been confirmed.After annealing in H₂ atmosphere at 500°C for 2h, enhanced room temperature ferromagnetism has been observed in the paramagnetic Zn_0.98Mn_0.02O powders synthesized by sol–gel method. Mn ions in interstitial sites have been clearly resolved by Raman measurement in the as-prepared Zn_0.98Mn_0.02O powders and those annealed in Ar and air, while hydrogenation facilitates the interstitial Mn ions to substitute the Zn sites. The structural characterizations have confirmed the incorporation of the interstitial H and excluded the ferromagnetic contribution of O vacancies. Our results clearly demonstrate the ferromagnetic mediation between the neighboring substituted Mn²⁺ ions by the interstitial H ions.

Keywords: Diluted magnetic semiconductor; ZnO; Hydrogenation; Ferromagnetism

Enhanced room temperature ferromagnetism in hydrogenated Zn_0.98Mn_0.02O by Hua Zhang; Sai Qin; Yanqiang Cao; Zaixing Yang; Lifang Si; Wei Zhong; Di Wu; Mingxiang Xu; Qingyu Xu (pp. 421-423).

Keywords: Diluted magnetic semiconductor; ZnO; Hydrogenation; Ferromagnetism

Synthesis of vertically aligned carbon nanotubes on carbon fiber by S. Rahmanian; A.R. Suraya; R. Zahari; E.S. Zainudin (pp. 424-428).

► Vertically aligned carbon nanotubes were synthesized on the surface of carbon fiber. ► Compact and adhesive coating of catalyst on carbon fiber was achieved without the application of additional pre-deposited substrate. ► Acid treatment, ultrasonic assisted catalyst-dip coating and calcination were the main steps, which provided appropriate catalyst coating. ► Two types of solvent, acetone and ethanol, were examined in dip coating step and acetone was found more effective to produce dense catalyst coating.In spite of several researches to synthesize carbon nanotubes (CNTs) on carbon fiber (CF), most have obtained entangled nanotubes versus the aligned form. In this study, by controlling catalyst coating technique, vertically aligned CNT were grown on CF through chemical vapor deposition (CVD). Activated fiber surface originated from acid treatment, compact coverage of catalyst precursor via applying ultrasonication in appropriate solvent, followed by calcinating were effective parameters which resulted in growing bundles and vertically aligned CNT on CF. Ethanol and acetone were examined as solvent thereby spot catalyst coating was created from the former while film coverage produced from the later and resulted in distinctive CNT morphology.

Keywords: Carbon nanotube; Vertically aligned morphology; Chemical vapor deposition; Carbon fiber

Synthesis of vertically aligned carbon nanotubes on carbon fiber by S. Rahmanian; A.R. Suraya; R. Zahari; E.S. Zainudin (pp. 424-428).

Keywords: Carbon nanotube; Vertically aligned morphology; Chemical vapor deposition; Carbon fiber

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Applied Surface Science (v.271, #)