Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Applied Surface Science (v.258, #13)
Field emission properties of carbon nanotubes in a stretchable polydimethylsiloxane matrix by Hui Ding; Tao Feng; Yiwei Chen; Zhuo Sun (pp. 5191-5194).
► Carbon nanotubes embedded in polydimethylsiloxane matrix as conducting films. ► The film maintains electric conductivity at the strain up to 55%. ► The field emission properties with strain are also investigated. ► The formed microclusters on the surface change field emission performance.The stretchable conducting films are fabricated by screen-printing method combined with polydimethylsiloxane (PDMS) infiltration. This film is a hybrid composite film formed by embedding carbon nanotubes in a PDMS matrix. The sheet resistance is measured with the tensile strain, and the film maintains electric conductivity at the strain up to 55%. The composite film is used as cathode to measure the field emission properties under varying stretching conditions, which is sensitive to the strain. Through the images of field emission scanning electron microscope, the formed pinholes on the surface are found to be contributed to the change in field emission performance.
Keywords: Carbon nanotube; Polydimethylsiloxane; Field emission; Stretchable films
MOKE study of hybrid magnetic thin films: Permalloy on molecular self-assembled monolayer by Saleem G. Rao (pp. 5195-5199).
► MOKE study of Permalloy-Py thin films deposited on self-assembled monolayer-SAM. ► Initial cluster like growth of Py on non-polar SAM gives paramagnetic response. ► Thick film of Py on non-polar SAM shows ferromagnetic behavior. ► Both thin and thick film of Py on polar SAM illustrated ferromagnetic behavior. ► Surface chemistry of SAM can tune-up the magnetic properties of ferromagnetic thin films.This paper reports the magneto optical Kerr effect (MOKE) study of magnetic thin film (of Permalloy-Py) deposited on molecular self-assembled monolayer (SAM) of different organic functional groups (OFGs), polar (–COOH/NH2) and non-polar (–CH3) on Au and Si/SiO2 substrates. MOKE study of these hybrid films demonstrated the change in magnetic behavior of Py due to its initial uniform growth on polar SAM and cluster like growth on non-polar SAM. Clear difference in MOKE response in terms of coercivity, shape of hysteresis loops, and even paramagnetic response was observed for ferromagnetic thin film (∼5nm) of Py deposited on polar and non-polar SAM. For thick (∼10nm) film Py deposited on SAM MOKE hysteresis loops were almost square on all SAM (polar and non-polar) with some difference in coercivity due to observed contrast in initial morphology arising from the difference in reactive nature of the OFG of SAM. These results suggest an alternative way for tuning the magnetic properties of the ferromagnetic thin film by OFG of SAM. Furthermore, with patterning flexibility of SAM at micron/nano scale, these finding can be used to create template of magnetic thin film.
Keywords: MOKE study; Hybrid thin films; Self-assembled monolayers; Thin film template; Ferromagnetic thin films
Stress control in ZnO films on GaN/Al2O3 via wet oxidation of Zn under various temperatures by K.M.A. Saron; M.R. Hashim; M.A. Farrukh (pp. 5200-5205).
► Epitaxial ZnO thin films were synthesized, using the wet oxidation process. ► High quality of synthesized ZnO films were obtained by applying two temperatures (420 and 470°C). ► ·The lattice constant of ZnO films shrinked by increasing oxidation temperature through increase of oxygen diffusion in ZnO lattice. ► ·It is possible to grow controllable stress of ZnO on GaN substrate using simple method for high quality thin films.Stress and lattice constants are significant factors considered in evaluating the deformation mode of crystalline materials. Zinc oxide (ZnO) nanostructured thin films were prepared via the process of wet oxidation of Zn at temperatures varying from 420 to 570°C. Structural, elemental and optical characterizations were carried out using various techniques, to investigate the properties of the samples. Scanning electron microscopy (SEM) images showed improvement in the ZnO structure and the grain size of the ZnO became larger as the oxidation temperature was increased, while maintaining a constant flow rate of wet oxygen. X-ray diffraction (XRD) patterns also showed that ZnO films suffered from compressive stress due to elongation in the lattice constant. With increase in the oxidation temperature, the compressive stress became tensile stress because of the decrease in the lattice constants. Photoluminescence (PL) spectra revealed the influence of stress on the energy band gap, with wet oxidation further giving rise to the transition of stress from compressive to tensile.
Keywords: ZnO; GaN/Al; 2; O; 3; Wet oxidation; Nanostructures; Stress
Structural, optical and magnetic properties of Zn0.97− xCu xCr0.03S nanoparticles by D. Amaranatha Reddy; G. Murali; B. Poornaprakash; R.P. Vijayalakshmi; B.K. Reddy (pp. 5206-5211).
.Display Omitted► Zn0.97− xCu xCr0.03S nanoparticles were synthesized by chemical co-precipitation method. ► Synthesized ZnS:(Cr,Cu) nanoparticles were in cubic phase. ► Luminescence quenching was observed in doped samples compared to the undoped samples. ► FTIR spectra excludes that intact EDTA simply coexists with the ZnS nanoparticles. ► Enhancement of RTFM was observed in Cu co-doped samples.Zn0.97− xCu xCr0.03S ( x=0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoparticles were synthesized by chemical co-precipitation method for the first time. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive analysis of X-rays (EDAX). Diffuse reflectance spectra (DRS) and photoluminescence spectra (PL). EDAX spectra confirmed the presence of Cr and Cu in the samples with expected stoichiometry. XRD patterns showed that dopant atoms of Cr and Cu were incorporated at the Zn sites in the cubic structure without disturbing the original ZnS cubic structure. However, at a concentration of 5at.% the planes corresponding to Cu were observed. This shows the immiscibility of Cu in ZnS for a concentration of 5at.%. Reflectance of Cu co-doped samples decreased with increase in Cu concentration. Photoluminescence for pure ZnS was observed in the blue region. 1at.% Cu doping in ZnS:Cr resulted in a significant enhancement of PL intensity. Higher dopant concentrations resulted in a strong quenching of PL intensity. PL emission peak showed a red shift with increase in Cu content. FTIR studies revealed that the nanoparticles were sterically stabilized by EDTA. Magnetization studies indicated that Cu co-doping enhanced significantly the room temperature ferromagnetism of the samples.
Keywords: ZnS:Cr; Cu co-doping; DRS; PL; Room temperature ferromagnetism
Aligned carbon nanotube array functionalization for enhanced atomic layer deposition of platinum electrocatalysts by Arrelaine A. Dameron; Svitlana Pylypenko; Justin B. Bult; K.C. Neyerlin; Chaiwat Engtrakul; Christopher Bochert; G. Jeremy Leong; Sarah L. Frisco; Lin Simpson; Huyen N. Dinh; Bryan Pivovar (pp. 5212-5221).
Surface chemical treatments impact the nucleation and uniformity of growth of Pt catalysts fabricated into carbon nanotube arrays by atomic layer deposition. The carbon functionalizations and their impacts on the growth of the Pt catalyst films are characterized and the electrochemical performance of the most promising fabrication routes are demonstrated.Display Omitted► Surface functionalization of CNT surfaces influences the growth of Pt by ALD inside aligned CNT arrays. ► Pt density and uniformity inside arrays depends strongly on the gasses used for functionalization. ► Ar plasma blocks nucleation, O2 plasma and trimethylaluminum treatments enhance uniformity. ► Generation/reduction of oxygen rich defect sites is the key to promote/block Pt ALD nucleation.Uniform metal deposition onto high surface area supports is a key challenge of developing successful efficient catalyst materials. Atomic layer deposition (ALD) circumvents permeation difficulties, but relies on gas-surface reactions to initiate growth. Our work demonstrates that modified surfaces within vertically aligned carbon nanotube (CNT) arrays, from plasma and molecular precursor treatments, can lead to improved catalyst deposition. Gas phase functionalization influences the number of ALD nucleation sites and the onset of ALD growth and, in turn, affects the uniformity of the coating along the length of the CNTs within the aligned arrays. The induced chemical changes for each functionalization route are identified by X-ray photoelectron and Raman spectroscopies. The most effective functionalization routes increase the prevalence of oxygen moieties at defect sites on the carbon surfaces. The striking effects of the functionalization are demonstrated with ALD Pt growth as a function of surface treatment and ALD cycles examined by electron microscopy of the arrays and the individual CNTs. Finally, we demonstrate applicability of these materials as fuel cell electrocatalysts and show that surface functionalization affects their performance towards oxygen reduction reaction.
Keywords: Fuel cell; Catalyst; Atomic layer deposition (ALD); Carbon nanotube; Aligned carbon nanotube array; Platinum; Proton exchange membrane; Polymer electrolyte membrane; Plasma; Functionalization; Nucleation
Influence of sputtering power on composition, structure and electrical properties of RF sputtered CuIn1− xGa xSe2 thin films by Zhou Yu; Chuanpeng Yan; Tao Huang; Wen Huang; Yong Yan; Yanxia Zhang; Lian Liu; Yong Zhang; Yong Zhao (pp. 5222-5229).
► We investigated the effect of sputtering power on structure and properties of RF sputtered CIGS films. ► At high sputtering power, CIGS films exhibit Cu-poor composition feature and partly amorphous phase structure. ► The 50W and 100W as-deposited films exhibit metal and semiconductor character, respectively. ► Annealed films exhibit improved crystalline quality and almost the same composition as the as-deposited ones.In this study, Cu(In1− xGa x)Se2 (CIGS) thin films were deposited at room temperature by one step radio frequency (RF) magnetron sputtering process. An one-stage vacuum annealing process without selenization was performed to improve properties of the films. Influences of sputtering power on composition, structure and electrical properties of the as-deposited and annealed films were investigated. As the sputtering power not exceeding a proper power of 100W, the as deposited and annealed films show near stoichiometric composition and polycrystalline chalcopyrite structure. The annealed films exhibit almost the same composition as the as-deposited ones. All the sputtered and annealed films exhibit uniform and compact surface morphology without peeling and cracking. The electrical conductivity measured in 50–290K range reveal that the 50W and 100W deposited films exhibit metal and semiconductor character, respectively. The 100W deposited film present data consist with thermoionic emission at high temperatures of 200–290K. However, Mott law with the variable range hopping mechanism is predominant in the low temperature region.
Keywords: Cu(In,Ga)Se; 2; thin films; Sputtering; Stoichiomertic composition; Annealing
Increased detection of human cardiac troponin I by a decrease of nonspecific adsorption in diluted self-assembled monolayers by Jun Ren; Xiuqing Ding; John J. Greer; Karthik Shankar (pp. 5230-5237).
► Self-assembled monolayer-based sandwich immunoassay for cardiac troponin I (cTnI). ► Fundamental study of specific and non-specific binding at functionalized gold surface. ► Diluted mixed monolayer suppresses non-specific binding. ► Nature of the diluting (non-binding) molecule controls non-specific binding. ► cTnI detection limit of 10ng/ml achieved without enzymatic amplification.In this paper, we tested the hypothesis that there is an increased sensitivity for detecting and measuring disease biomarkers (such as human cardiac troponin I, cTnI) by a decrease of nonspecific adsorption in diluted self-assembled monolayers (SAMs) on planar sputtered gold films. Combining grazing angle Fourier-transform infrared spectroscopy (FT-IR) and antibody–antigen–antibody (sandwich) fluorescence-based immunoassay, we examined the relationship of sensitivity, specificity of detection of cTnI and the level of nonspecific protein adsorption in the following SAMs: pure MHA (16-mercaptohexadecanoic acid, 1mM, with head COO−, x=1.0), a mixed SAM comprising MHA (0.1mM) and UDT (1-undecane thiol, 0.9mM, with hydrophobic head CH3, x=0.1UDT), and a mixed SAM comprising MHA (0.1mM) and MUD (11-mercapto-1-undecanol, 0.9mM, with hydrophilic head OH, x=0.1MUD). Our data revealed that nonspecific binding to SAMs is favored in the following order: CH3>COO−>OH, consistent with previous studies. Compared with pure SAMs, diluting MHA SAMs with MUD increases the sensitivity of cTnI, whereas diluted MHA SAMs with UDT has the same sensitivity of detection of cTnI, suggesting it is the nature of the second diluting thiol that plays an important role on the amount of adsorbed protein on the surface. We obtained a 10-fold increase in the limit of detection of cTnI to 10ng/ml using x=0.1MUD due to a decrease of nonspecific binding. Further, specific binding between the antigen cTnI and its antibody is unaltered on pure and diluted SAMs.
Keywords: Nonspecific protein adsorption; Immunoassay; ELISA; Cardiac troponin I; 16-Mercaptohexadecanoic acid; 1-Undecane thiol; 11-Mercapto-1-undecane; Self-assembled monolayer; Gold film
Preparation, characterization and mechanical properties of microarc oxidation coating formed on titanium in Al(OH)3 colloidal solution by Y. Li; B. Yao; B.Y. Long; H.W. Tian; B. Wang (pp. 5238-5243).
► MAO coating is grown on titanium in Al(OH)3 colloidal solution. ► Coating is composed by dominant rutile TiO2. ► Coating elastic modulus is up to 145GPa, larger than reported previously. ► In 17–23A/dm2 range produced coatings are compact and solid.A ceramic coating with thickness of 20–70μm was grown on titanium plate in Al(OH)3 colloidal solution by microarc oxidation (MAO) in constant current mode. It is found that the as-grown coating consists of rutile TiO2 phase together with a thin layer of Ai2TiO5 phase near the surface of the coating. After removing the Ai2TiO5 layer by polishing, a single phase of rutile TiO2 coating is achieved, which is different from results reported previously, where the coating is usually composed of two phases of rutile and anatase TiO2. It is suggested that the formation of the coating with single phase of rutile TiO2 is related to the existence of Al(OH)3 in the solution. The growth rate of the coating increases with increasing current density in the range of 17–23A/dm2, but it increases little in the range of 23–30A/dm2. The rutile TiO2 coating looks compactness and solidity in the coating grown in the density range of 17–23A/dm2 but looseness and insubstantiality in the range of 23–30A/dm2. The hardness and elastic modulus of the rutile TiO2 decreases with the density increasing. The mechanism of formation of the coating is discussed in the present work.
Keywords: Microarc oxidation; Colloidal; Titanium; Rutile; Aluminum titanate
Porous NiTi surfaces for biomedical applications by Z. Huan; L.E. Fratila-Apachitei; I. Apachitei; J. Duszczyk (pp. 5244-5249).
► NiTi was surface modified by plasma electrolytic oxidation in Na3PO4 electrolyte. ► Sub-micron sized pores were generated at 300V. ► O, Ti, P, Ni and a Ni/Ti atomic ratio of 0.4 were detected by EDS analyses. ► Wettability and surface free energy increased after oxidation. ► Attractive surface features for biomedical applications.In this study, the NiTi shape memory alloy was surface modified by plasma electrolytic oxidation (PEO) in Na3PO4 with the aim to produce porous NiTi surfaces for biomedical applications. The oxidation was performed potentiostatically and the characteristics of the resultant surfaces were compared with those obtained in NaAlO2/NaPO2H2 under similar conditions.Surfaces with sub-micron sized pores could be produced in Na3PO4 electrolyte at 300V. The process was accompanied by intense gas evolution and enhanced thermal effects relative to the NaAlO2/NaPO2H2 electrolyte. The EDS analyses revealed the presence of O, Ti, P, Ni, and a Ni/Ti atomic ratio of 0.4 suggesting preferential oxidation of titanium during the process and depletion of Ni from the surface. No crystalline oxide phases were detected by X-ray diffraction (XRD). By comparison, the layers formed in NaAlO2/NaPO2H2 consisted of crystalline Al2O3 and the Ni/Ti atomic ratio was 0.74. Following oxidation, the wettability and surface free energy of NiTi increased significantly.The findings of this study indicate that the PEO process shows potential for expanding the biofunctionality of NiTi.
Keywords: NiTi shape memory alloy; Plasma electrolytic oxidation; Porous layers; Biomedical applications
Elaboration and characterization of sol–gel derived ZrO2 thin films treated with hot water by Mun Teng Soo; Niki Prastomo; Atsunori Matsuda; Go Kawamura; Hiroyuki Muto; Ahmad Fauzi Mohd Noor; Zainovia Lockman; Kuan Yew Cheong (pp. 5250-5258).
► Preparation of ZrO2 thin films via sol–gel route by spin-coating method. ► Film thickness and refractive index varied as a function of molar ratio of EtOH during sol preparation and annealing temperature applied. ► Tetragonal ZrO2 formed after annealing at 400°C. ► Crystallinity of ZrO2 was enhanced by increasing molar ratio of EtOH. ► A hot-water treatment reduced film thickness and improved crystallinity of sol–gel derived oxide.We describe the preparation and characterization of zirconia (ZrO2) thin films via sol–gel route by spin-coating method. By utilizing alkoxides Zr[O(CH2)3CH3]4 in the presence of ethanol (EtOH), nitric acid and acetylacetone as a chelating agent, a stable sol of ZrO2 was obtained. Smooth surface morphology with nano-cracks was exhibited for all ZrO2 thin films being fabricated. The film thickness varied from 39 to 206nm depending on the molar ratio of EtOH during the sol preparation and also annealing temperature applied. All ZrO2 films possess high optical transmittance. Refractive index of the thin film was ranging from 1.6 to 2.4 depending on molar ratio of EtOH and annealing temperature. Tetragonal phase of ZrO2 was formed after annealed at 400°C. Crystallinity of ZrO2 was enhanced by increasing molar ratio of EtOH. Crystallite size of tetragonal ZrO2 was ranged from 3.0 to 9.9nm. A hot-water treatment reduced the film thickness and further improved crystallinity of the sol–gel derived oxide.
Keywords: Zirconia (ZrO; 2; ); Thin film; Ethanol solvent; Thickness; Refractive index; Sol–gel
A comparative study on TiO2 doped hybrid solar cells by Teoman Özdal; Yakup Hameş; Erdem Aslan (pp. 5259-5264).
► We produced various TiO2 based hybrid solar cell morphologies. ► Spin coating and doctor blade techniques were used as low cost production methods. ► All the production processes were carried out under normal laboratory conditions. ► Economy and convenience in the production has been provided. ► Also, sandwich structured n-TiO2/p-P3HT PV devices were produced and investigated.In this study, n-type titanium (IV) oxide (TiO2) and p-type poly (3-hexylthiophene-2,5-diyl) (P3HT) structured various photovoltaic (PV) devices have been produced onto indium tin oxide (ITO) coated glass substrates. For the economy and simplicity, spin coating and doctor blading deposition methods were used in normal atmospheric conditions. The effect of the device morphology on the efficiency of the solar cells was investigated by applying various morphologies such as classic and optimized p–n junctions, bulk heterojunction (BHJ) and sandwich structures, respectively. Electrical characterizations of the devices were obtained under AM 1.5G (100mW/cm2) solar illumination.
Keywords: TiO; 2; P3HT; Hybrid; Solar cell; Morphology
Effect of dangling bonds of ultra-thin silicon film surface on electronic states of internal atoms by Eiji Kamiyama; Koji Sueoka (pp. 5265-5269).
► Dangling bonds at surfaces of one or both sides of film were directly treated. ► The impacts on the electronic states of the internal atoms were estimated. ► Electronic states appeared in the midgap by removing terminated H at surfaces. ► The concentration at 18th layer in a 36-layer model is estimated at 1.2×1014cm−3. ► This concentration is not so low and may affect device performances.We investigate how dangling bonds at the surface of ultra-thin films affect electronic states inside the film by first principles calculation. In the calculation models, dangling bonds at the surface are directly treated, and the impact on the electronic states of the internal atoms was estimated. Models with a H-terminated surface at both sides have no state in the bandgap. Whereas, new states appear at around the midgap by removing terminated H at surfaces of one or both sides. These mid-gap states appear at all layers, the states of which decrease as the layer moves away from the surface with dangling bonds. The sum of local DOS corresponds to the number of dangling bonds of the model. If the activation rate is assumed as 2.0×10−5, which is an ordinary value of thermal oxide passivation on Si (100) surface, volume concentration and surface concentration at the 18th layer from the surface in a 36-layer model are estimated to be 1.2×1014cm−3 and 1.5×109cm−2, respectively. These numbers are comparable to the values, especially the dopant volume concentration of Si substrate used in current VLSI technology (∼1015cm−3). Therefore, the midgap states inside ultra-thin films may degrade performance of the FinFETs.
Keywords: Silicon; Film; Density of states; Dangling bond; Mid-gap states
Contamination of stainless steel in an electrospray ionization source by J. Doff; D. Douce; G. Jones; E.V. Koroleva; P. Skeldon; G.E. Thompson (pp. 5270-5282).
► Investigation of contamination of stainless steel within the electrospray ionization source. ► The contamination contains both inorganic and organic components. ► The contamination forms ring-like shapes and then porous self-organizing nodules. ► Contamination builds up by a similar mechanism to electrostatic spray deposition.The contamination of the surface of 316L stainless steel in the electrospray ionization source of a mass spectrometer is investigated using an accelerated method of contamination from a mixture of human blood plasma, diluted in methanol, and a water/acetonitrile mobile phase. Solid contaminants containing organic and inorganic components are identified. The morphology and composition of the contamination are shown to depend upon the orientation and temperature of the stainless steel, with the morphology showing self-organizing features as the contamination builds. A model is proposed to explain the morphology, involving rapid evaporation of the droplets that impinge on the stainless steel surface.
Keywords: Stainless steel; Electrospray; Mass spectrometer; Contamination
Comparison of the protection effectiveness of acrylic polyurethane coatings containing bark extracts on three heat-treated North American wood species: Surface degradation by Duygu Kocaefe; Sudeshna Saha (pp. 5283-5290).
► Surface degradation of coated heat-treated wood species during aging was studied. ► A coating was developed to delay the discoloration and degradation of wood. ► The discoloration of coated jack pine was much less compared to birch and aspen. ► The discoloration was due to the surface degradation of wood beneath the coating. ► Chain scission of urethane main linkage of the coating was noticed by XPS analysis.High temperature heat-treatment of wood is a very valuable technique which improves many properties (biological durability, dimensional stability, thermal insulating characteristics) of natural wood. Also, it changes the natural color of wood to a very attractive dark brown color. Unfortunately, this color is not stable if left unprotected in external environment and turns to gray or white depending on the wood species. To overcome this problem, acrylic polyurethane coatings are applied on heat-treated wood to delay surface degradations (color change, loss of gloss, and chemical modifications) during aging. The acrylic polyurethane coatings which have high resistance against aging are further modified by adding bark extracts and/or lignin stabilizer to enhance their effectiveness in preventing the wood aging behavior. The aging characteristic of this coating is compared with acrylic polyurethane combined with commercially available organic UV stabilizers. In this study, their performance on three heat-treated North American wood species (jack pine, quaking aspen and white birch) are compared under accelerated aging conditions. Both the color change data and visual assessment indicate improvement in protective characteristic of acrylic polyurethane when bark extracts and lignin stabilizer are used in place of commercially available UV stabilizer. The results showed that although acrylic polyurethane with bark extracts and lignin stabilizer was more efficient compared to acrylic polyurethane with organic UV stabilizers in protecting heat-treated jack pine, it failed to protect heat-treated aspen and birch effectively after 672h of accelerated aging. This degradation was not due to the coating adhesion loss or coating degradation during accelerated aging; rather, it was due to the significant degradation of heat-treated aspen and birch surface beneath this coating. The XPS results revealed formation of carbonyl photoproducts after aging on the coated surfaces and chain scission of CN of urethane linkages.
Keywords: Heat-treated wood; Acrylic polyurethane coatings; Bark extracts; Accelerated aging; Color measurement; Surface characterizations
Multicarboxylic hyperbranched polyglycerol modified SBA-15 for the adsorption of cationic dyes and copper ions from aqueous media by Zhengji Chen; Li Zhou; Faai Zhang; Chuanbai Yu; Zhibo Wei (pp. 5291-5298).
► Multicarboxylic HPG modified mesoporous SBA-15 was synthesized for the first time. ► The multicarboxylic HPG can endow SBA-15 with numerous negative charged carboxylic groups. ► The SBA/HPG-COOH showed much higher adsorption capacity and selectivity than SBA-15. ► The method to modification of SBA-15 can also be extended to other substrates.The aim of the present work was to investigate the potential of multicarboxylic hyperbranched polyglycerol (HPG) modified mesoporous SBA-15 (SBA/HPG-COOH) as adsorbent for the removal of cationic dyes or/and heavy metal ions from aqueous media. The SBA/HPG-COOH adsorbents can be facilely synthesized through two steps: in situ anionic ring-opening polymerization of glycidol and further modification of hydroxyl groups by succinic anhydride. The resulting SBA/HPG-COOH was characterized by means of FTIR, TGA, XRD, SEM and nitrogen adsorption–desorption isotherms. The results demonstrate that the SBA/HPG-COOH was successfully synthesized and the density of carboxylic groups on the SBA/HPG-COOH is calculated to be as high as 1.5mmol/g, posing a powerful base for adsorbing cationic adsorbates. Four kinds of dyes and copper ions were chosen as representatives to investigate the adsorption ability of SBA/HPG-COOH. The SBA/HPG-COOH adsorbent showed quick adsorption rate, high adsorption capacity (e.g., its saturated adsorption capacity for methylene blue (MB) can reach 0.50mmol/g, while for unmodified SBA-15 is lower than 0.05mmol/g), and high selectivity for cationic adsorbates. The fitness of Langmuir adsorption model and pseudo second-order kinetics on describing the adsorption isotherm and kinetics of SBA/HPG-COOH for MB dye was examined, respectively. It is believed that this robust SBA/HPG-COOH adsorbent will find important application in removal of cationic adsorbates from aqueous solution.
Keywords: SBA-15; Hyperbranched polyglycerol; Adsorption; Dyes; Copper ions
Reduced graphene oxide paper by supercritical ethanol treatment and its electrochemical properties by Siyang Liu; Ke Chen; You Fu; Suyang Yu; Zhihao Bao (pp. 5299-5303).
► Treatment in supercritical ethanol as a green route was used to reduce the prefabricated graphene oxide paper. ► The reduction of the graphene oxide paper was confirmed by various characterization methods. ► The reduced graphene oxide paper, with a specific capacity of 89mAh/g, can be used as a binder-free anode for lithium battery.Graphene oxide (GO) paper was treated in supercritical ethanol as a green route for its reduction, which was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis and conductivity measurements. The reduced GO paper showed good electrochemical properties. As a sole component of the anode in lithium ion batteries, its specific capacity was comparable to those of free standing GO papers reduced by hydrazine or carbon nanotube paper. The GO paper reduced by supercritical ethanol can be a potential candidate for a binder-free anode in high performance lithium batteries.
Keywords: Graphene; Supercritical ethanol; Reduction; Lithium battery