Applied Catalysis B, Environmental (v.214, #C)
Editorial Board (IFC).
High hexitols selectivity in cellulose hydrolytic hydrogenation over platinum (Pt) vs. ruthenium (Ru) catalysts supported on micro/mesoporous carbon by P.A. Lazaridis; S.A. Karakoulia; C. Teodorescu; N. Apostol; D. Macovei; A. Panteli; A. Delimitis; S.M. Coman; V.I. Parvulescu; K.S. Triantafyllidis (1-14).
Display OmittedThe “one-pot” hydrolyltic hydrogenation of cellulose towards C2-C6 sugar alcohols has been recognized as one of the most promising biomass valorization routes for the production of high added-value chemicals. In this work, we studied the performance of Ru and Pt catalysts supported on micro/mesoporous activated carbon, in the hydrolytic hydrogenation of microcrystalline and ball-milled cellulose, in neat water, at 180 °C and at relatively low hydrogen pressure of 2 MPa. The impact of metal loading (1–5 wt.%), metal reduction method (H2 at 350 °C or NaBH4) and acidification (sulfonation) of the AC support on cellulose conversion and selectivity to the various products were systematically addressed. It was shown that Pt is significantly more selective towards hexitols (sorbitol and mannitol) compared to Ru, in glucose-rich reaction media, such as those offered by the easily hydrolyzed ball-milled cellulose. For example, the 5wt%Pt/AC-SO3H catalyst afforded hexitols yield of 69.5 wt.% (at 96.1% conversion) compared to 10.9 wt.% (at 95.2% wt.% conversion) obtained by the corresponding Ru catalyst, the latter being also selective towards glycerol and propane-1,2-diol (propylene glycol). A relatively moderate metal loading, such as in 3 wt.%Ru/AC-SO3H, was more favorable for hexitols production (44.5 wt.% yield, at 94.8 wt.% conversion) with Ru catalysts. These results were also verified by glucose hydrogenation experiments that were conducted at the same experimental conditions. Both Pt and Ru exhibited relatively high glucose hydrogenation activity towards hexitols, versus retro-aldol reactions that lead directly to smaller C2–C4 compounds, while the difference in the final product yields between the two metals was attributed to the higher hexitols hydrogenolysis (C―C cleavage) reactivity of Ru. HRTEM data showed the formation of metallic crystalline Pt and Ru nanoparticles (≤4 nm, depending on loading) as well as of amorphous oxygen-rich M(O)x δ+ phases, which were also confirmed by the XPS data. The presence of these phases which may be a source of acidity, as well as the bacisity of the parent AC used in this study, were mainly responsible for inducing isomerization, retro-aldol and dehydration reactions leading eventually to increased glycerol and propylene glycol selectivity, as was observed for both low-metal catalysts, i.e. 1 wt.% Pt or Ru/AC.
Keywords: Cellulose; Hydrolytic hydrogenation; Sugar alcohols; Platinum vs. ruthenium; Micro/mesoporous carbon;
Size-dependent plasmonic effects of M and M@SiO2 (M = Au or Ag) deposited on TiO2 in photocatalytic oxidation reactions by Ji Eun Lee; Sandipan Bera; Young Sik Choi; Wan In Lee (15-22).
Display OmittedMonodispersed Au nanoparticles (NPs) with sizes of 18, 26 and 34 nm and Ag NPs with sizes of 17, 25 and 33 nm, as well as their corresponding M@SiO2 core-shell NPs (M = Au or Ag), were selectively synthesized. The prepared individual plasmonic NPs were then loaded onto TiO2 and their size-dependent plasmonic effects in photocatalytic oxidation reactions were systematically analyzed. In the removal reactions of the organic compounds, aqueous salicylic acid (SA) and aniline, under UV–vis light irradiation, both the Au and Ag NPs significantly enhanced the catalytic activity of TiO2, while the smaller NPs were more effective. Although the Ag NPs show stronger LSPR effect than the Au NPs, the overall catalytic activity of the Ag/TiO2 systems was not higher than Au/TiO2, and their catalytic activity variation according to the size of plasmonic NPs was more sensitive for Ag/TiO2. The observed results seem to be due to the LSPR sensitization effect. It was also found that the M@SiO2 NPs were significantly more effective than the bare M NPs in enhancing the photocatalytic activity of TiO2 and the size-dependent plasmonic effects of the M@SiO2 NPs were quite different from those of the bare M NPs. In regrading to catalytic activity enhancement, the optimum sizes of the Au and Ag NPs for the Au@SiO2 and Ag@SiO2 NPs were determined to be 26 and 25 nm, respectively. Moreover, the Ag@SiO2 NPs, which generate stronger LSPR, were more effective than the Au@SiO2 NPs. Consequently, Ag25@SiO2/TiO2 demonstrates the highest activity in decomposing SA and aniline, which is 3.8 and 2.5 times, respectively, that of the bare TiO2.
Keywords: Plasmonic photocatalyst; Photocatalytic oxidation reaction; LSPR effect; Au and Ag nanoparticle; Au@SiO2 and Ag@SiO2;
Enhanced photocatalytic inactivation of Escherichia coli by a novel Z-scheme g-C3N4/m-Bi2O4 hybrid photocatalyst under visible light: The role of reactive oxygen species by Dehua Xia; Wanjun Wang; Ran Yin; Zhifeng Jiang; Taicheng An; Guiying Li; Huijun Zhao; Po Keung Wong (23-33).
Display OmittedBiohazards are widely present in wastewater, and contaminated water can arouse various waterborne diseases. Therefore, effective removal of biohazards from water is a worldwide necessity. In this study, a novel all-solid-state Z-scheme g-C3N4/m-Bi2O4 heterojunction was constructed using a facile hydrothermal approach. Using the optimum g-C3N4/m-Bi2O4 (1:0.5), 6 log10 cfu/mL of E. coli K-12 could be completely inactivated within 1.5 h under visible light irradiation, while only 1.2 log10 cfu/mL and 3.2 log10 of E. coli K-12 were inactivated by pure g-C3N4 and Bi2O4 under the same experimental conditions respectively. Emphasis was placed on identifying how the charge transfers across the g-C3N4/m-Bi2O4 heterojunction and a Z-scheme charge transfer mechanism was verified by reactive species trapping and quantification experiments. The Z-scheme charge separation within g-C3N4/m-Bi2O4 populated electrons and holes into the increased energy levels, thereby enabling one-step reduction of O2 to H2O2 and facilitating more generation of holes. This greatly accelerated photocatalytic efficiency on the inactivation of E. coli. Moreover, microscopy images indicate that cell structures were damaged and intracellular components were leaked out during the photocatalytic inactivation process. This study suggests that the newly fabricated Z-scheme g-C3N4/m-Bi2O4 is a promising photocatalyst for water disinfection.
Keywords: E. coli inactivation; g-C3N4/m-Bi2O4; Charge transfer; Z-scheme; Bacterial destruction;
Photogeneration of reactive oxygen species from biochar suspension for diethyl phthalate degradation by Guodong Fang; Cun Liu; Yujun Wang; Dionysios D. Dionysiou; Dongmei Zhou (34-45).
Display OmittedIn this study, the photogeneration of reactive oxygen species (ROS) from biochar suspension was investigated. The characterizations of biochar particles before and after photochemical reactions were analyzed by using FTIR, Raman, XPS and electron paramagnetic resonance (EPR) techniques. It was found that the model pollutant diethyl phthalate (DEP) was efficiently degraded and partially mineralized under UV and simulated solar lights in biochar suspension, with hydroxyl radicals (•OH) and singlet oxygen (1O2) as the dominant ROS. EPR coupled with chemical probe methods and free radical quenching studies were used to quantify and elucidate the formation mechanism of •OH and 1O2. The results indicated that biochar carbon matrix (BCM) accounted for 63.6%–74.6% of •OH and 10%–44.7% of 1O2 formation, while dissolved organic matter (DOM) derived from biochar generated 46.7%–86.3% of 1O2 and 3.7%–12.5% of •OH. BCM-bound persistent free radicals (BCM-PFRs) and quinone-like structure of BCM (BCM-Q) were the predominant factors affecting •OH and 1O2 formation from BCM under light. Detailed ROS generation pathways are proposed as: (i) DOM from biochar particles contributes to •OH and 1O2 formation via light-induced energy and electron transfer processes; (ii) BCM-Q forms excited triplet states (3[BCM-Q]*) under light irradiation and induces the formation 1O2; (iii) UV promotes the formation of BCM-PFRs, which transfer electrons to oxygen to form superoxide anion radical (O2 • −), further yielding H2O2; and (iv) H2O2-dependent pathways including BCM-PFRs activation and photo-Fenton reaction are primarily responsible for •OH production. Furthermore, BCM exhibits the excellent reusability towards DEP degradation during the three cycles under light.
Keywords: Biochar; Photochemical reactions; ROS; DEP degradation; PFRs;
Switching of semiconducting behavior from n-type to p-type induced high photocatalytic NO removal activity in g-C3N4 by Jianmin Luo; Guohui Dong; Yunqing Zhu; Zhong Yang; Chuanyi Wang (46-56).
We demonstrated that the switching of the semiconducting behavior from n-type to p-type can efficiently improve the photocatalytic activity of g-C3N4 for nitric oxide (NO) removal about 3.5 times. The reason is that the incorporated Cl• formed an acceptor level above the VB. This new formed intermediate level improves the visible light absorption efficiency while favors electron excitation and suppresses the recombination of the photogenerated carriers of g-C3N4.Display OmittedThe utilization of photocatalytic technology to remove air pollutants has attracted global interest. However, it still suffers from low removal activities under visible light irradiation. In this study, we demonstrated that the switching of the semiconducting behavior from n-type to p-type can efficiently improve the photocatalytic activity of g-C3N4 for nitric oxide (NO) removal about 3.5 times. This is due to that such switching could change the majority of carriers in g-C3N4 from electrons to holes. Interestingly, the photocatalytic removal of NO in both n-type and p-type g-C3N4 is proceeded via hole oxidation. More importantly, p-type g-C3N4 displays strong stability in both photocatalytic performance and crystal structures. This study provides a new strategy to improve the photocatalytic activity of semiconductors for air pollution removal.
Keywords: p-type g-C3N4; Semiconducting behavior switching; NO removal; Photocatalysis; Charge carriers;
Effect of the support on the hydrodeoxygenation of m-cresol over molybdenum oxide based catalysts by Vinicius O.O. Gonçalves; Carmen Ciotonea; Sandrine Arrii-Clacens; Nadia Guignard; Christelle Roudaut; Julie Rousseau; Jean-Marc Clacens; Sébastien Royer; Frédéric Richard (57-66).
Display OmittedThe hydrodeoxygenation (HDO) of m-cresol was investigated over supported molybdenum oxide catalysts at 340 °C under 4 MPa as total pressure. All catalysts were fully characterized using several techniques such as atomic absorption, N2 physisorption, XRD, H2-TPR, NH3-TPD, Raman spectroscopy, TEM analysis and oxygen chemisorption. It was noted that the reducibility of molybdenum species depends on the support used and follows the same order than the one determined from the HDO activity, i.e. MoOx/Al2O3 > MoOx/SBA–15 > MoOx/SiO2. In addition, the use of an ordered mesoporous silica support (SBA-5) or an acidic support (Al2O3) favored significantly the dispersion of MoOx particles compared to SiO2.Under these experimental conditions, m-cresol transformation underwent through two parallel deoxygenation routes which involved either the direct C―O bond scission leading to toluene (DDO route), or the total hydrogenation of the aromatic ring yielding mainly to a mixture of methylcyclohexene isomers (HYD route). Regardless of the support used, the DDO route was always predominant. A reaction mechanism was proposed to explain the formation of toluene, the main product observed from HDO of m-cresol. To explain the formation of this aromatic, a selective adsorption through the oxygen atom of the phenolic reactant on oxygen vacancies, acting as HDO active sites, was proposed.
Keywords: m-Cresol; HDO; MoOx/SBA-15; MoOx/SiO2; MoOx/Al2O3;
Catalytic transfer hydrogenation of butyl levulinate to γ-valerolactone over zirconium phosphates with adjustable Lewis and Brønsted acid sites by Fukun Li; Liam John France; Zhenping Cai; Yingwen Li; Sijie Liu; Hongming Lou; Jinxing Long; Xuehui Li (67-77).
Display OmittedThe efficient production of γ-valerolactone (GVL) from renewable resources is attracting increasing attention in view of its wide application in fuel and synthetic chemistry. In this study, a series of novel and efficient zirconium phosphate catalysts were developed for the transfer hydrogenation of levulinate esters to GVL using isopropanol as the hydrogen donor. Experimental results show that 98.1% butyl levulinate conversion and 95.7% GVL yield can be achieved with ZrPO-1.00 at 483 K after 2.0 h. Intensive characterization of the synthesized catalysts using N2 adsorption-desorption, FT-IR, ICP-AES, XPS, NH3-TPD, Py-FTIR and XRD demonstrates that the physicochemical properties, particularly hydrophobicity, Lewis to Brønsted acid site ratio and Lewis acid site strength were subtly tuned via adjustment of the molar proportion of phosphorus to zirconium, which is responsible for excellent transfer hydrogenation activity. Furthermore, this optimized catalyst exhibits high stability and recyclability for at least ten reaction cycles. In addition, a plausible reaction pathway and catalytic mechanism are proposed.
Keywords: γ-Valerolactone; Butyl levulinate; Zirconium phosphate; Transfer hydrogenation; Catalytic mechanism;
The influence of different Cu species onto multi-copper-contained hybrid materials’ photocatalytic property and mechanism of chlorophenol degradation by Shengjie Xia; Xiaofeng Zhang; Xiaobo Zhou; Yue Meng; Jilong Xue; Zheming Ni (78-88).
Display OmittedIn this paper, we synthesized a series of novel layered double hydroxides (LDHs) based materials with different organic/inorganic Cu species (Cu3O/CuCr1–Cu2/SB–LDHs). The Cu species were distributed in the layers (defined as Cu1), intercalated between the layers (Cu2) and combined on the surface of the material (Cu3), respectively. The percentage of each Cu specie was adjusted to reveal the connection between different modifications and their photocatalytic activities as well as the modifications and the mechanism towards the chlorophenol (2,4,6-TCP) degradation. The experimental results showed that photodegradation of TCP varied due to different Cu species, the catalyst with the highest Cu concentration between the layers had the highest TCP degradation rate of 95.1%. In addition, the apparent quantum efficiency of different Cu3O/Cu1Cr–Cu2/SB–LDH materials was at the range of 0.42% to 0.60%, which was higher than that of CuCr–LDHs (0.21%) and CuCr–CuSB–LDHs (0.32%). The free radical tests showed that different Cu species determined the generation of hydroxyl radical, super oxide free radical and peroxy radicals, differently. These three radicals contributed to 46.2%, 22.5% and 10.9%, respectively, for TCP degradation during the photocatalytic reaction. Therefore, it is critical to study the influence of different Cu modifications to the improvement of photocatalytic reactivity and selectivity of Cu3O/Cu1Cr–Cu2/SB–LDH material. In addition, the intermediates, pathway and photoreaction mechanism of TCP degradation were also investigated in detail.
Keywords: Layered double hydroxides; Cu species; Photocatalysis; Chlorophenol (2,4,6-TCP); Active free radicals;
Study on the formation of photoactive species in XPMo12-nVnO40- HCl system and its effect on photocatalysis oxidation of cyclohexane by dioxygens under visible light irradiation by Senpei Tang; Jialuo She; Zaihui Fu; Shenyi Zhang; Zeyu Tang; Chao Zhang; Yachun Liu; Dulin Yin; Jianwei Li (89-99).
Vanadium atoms-substituted phosphomolybdic acids and their salts, in the help of O2, can react with HCl to form a photoactive species [POM-(VOHM)+Cl−](M for V or Mo)] and the latter should be responsible for the oxygenation of cyclohexane by O2 to cyclohexanol and cyclohexanone under visible light irradiation.Display OmittedThe formation of photoactive species in the Keggin-type XPMo12-nVnO40 polyoxometalates (POMs, n = 1-3, X = H+, tetramethyl (TMA). tetrabutyl (TBA) or cetyltrimethyl (CTMA) ammonium cation (Q+))-HCl system was researched in details by UV–vis and its photo-catalysis performance evaluated via the oxidation of cyclohexane by dioxygens (O2) in acetonitrile (MeCN) under visible light irradiation The results showed that the VV-O-M (M for VV or MoIV) sites of POM can capture HCl to form a protonated photoactive species (PA, POM-(VVOHM)+Cl−) and the solvent MeCN likely participates the formation of such PA species via weak coordination. This PA species, with a characteristic absorption band of 475 nm, a 51V-NMR chemical shift of −550 ppm and an oxidative potential of higher than 0.9 V, should be responsible for the present photo-catalysis oxidation. The formation of PA species was accelerated significantly with increasing the V atoms incorporated into POMs, but hampered seriously in the presence of slight excess water due to the replaced effect of water for the coordinated HCl and MeCN. Notably, such impediment effect of water was weakened obviously over the Q+-containing POMs due to a hydrophobicity of these POM's. As a result, most of the Q+-containing POMs showed a higher activity for this photo-catalysis reaction in MeCN-HCl-H2O media than the H+-containing counterparts. Isotope tracing test of water-containing heavy oxygen 18O (97%) in photo-catalysis reaction indicated that the oxygen atoms in water had partly contribution to the formation of cyclohexanol (ca.8.2%) and especially cyclohexanone (ca. 33.3%), which can drastically restrain chlorinated side reactions and thus improve cyclohexanone selectivity. Based on these findings, a free-radical mechanism initiated by the Cl atoms generated in the excited POM-(VVOHM)+Cl− species was proposed.
Keywords: Vanadium-substituted molybdophosphoric acids/salts; Photo-catalytic oxidation; Cyclohexane; Cyclohexanol; Cyclohexanone; Visible light;
The ILs-assisted electrochemical synthesis of TiO2 nanotubes: The effect of ionic liquids on morphology and photoactivity by P. Mazierski; J. Łuczak; W. Lisowski; M.J. Winiarski; T. Klimczuk; A. Zaleska-Medynska (100-113).
Display OmittedFacile and environmentally benign one-step titanium anodization method for TiO2 nanotubes (NTs) formation in a presence of ionic liquids (ILs) was proposed. Influence of the IL structure and its content in ethylene glycol electrolyte on morphology, surface properties and photoactivity of the TiO2 NTs was investigated. Possible interactions between IL and TiO2 NTs as well as the mechanism of NTs formation during anodic oxidation process were proposed. The outer diameter, wall thickness, and length of the IL-NTs were found to be proportionally related with increasing length of the hydrocarbon chain in the imidazolium cation of the IL (from 2 to 8), IL content, anodization potential and water content up to 10 vol.%. Moreover, for the first time, the effect of the IL’s structure on the UV–vis and Vis light-induced photoactivity of the IL-TiO2 NTs was presented, and the active species (•OH and O2 •− radicals) involved in the photocatalytic reaction of phenol degradation were determined. The sample that exhibited the highest photoactivity under Vis irradiation (0.63 μmol dm−3 min−1) and greatest amounts of generated •OH was TiO2 NTs prepared at anodization potential 90 V in the electrolyte containing 0.1 mol of 1-octyl-3-methylimidazolium tetrafluoroborate [OMIM][BF4] (represented by F− content) and 10 vol.% of water. Phenol degradation rate remained at level about 1.50 and 0.42 μmol dm−3 min−1 after 60 min of UV–vis and Vis irradiation after four cycles in the presence of [OMIM][BF4] and thus obtained IL-NTs exhibited photostability. The reaction proceeds under mild reaction conditions, is step economical and provides one-dimensional nanostructures that meet the specifications for use in diverse photocatalytic applications.
Keywords: TiO2 nanotubes; Ionic liquid; Electrochemical method; Phenol degradation; Visible light photoactivity; Nitrogen and boron doping;
Plasma-catalytic conversion of CO2 and CO2/H2O in a surface-wave sustained microwave discharge by Guoxing Chen; Thomas Godfroid; Nikolay Britun; Violeta Georgieva; Marie-Paule Delplancke-Ogletree; Rony Snyders (114-125).
Display OmittedThe conversion of CO2 and CO2/H2O mixtures on a TiO2 supported NiO catalyst in a pulsed surface-wave sustained microwave discharge has been investigated. The influence of the catalyst preparation method (conventional calcination (in air or Ar) vs. Ar plasma-assisted decomposition) on the CO2 conversion and its energy efficiency has been studied. The results demonstrate that the Ar plasma-treated catalyst is more active compared to the conventional calcined one. The plasma-treated catalyst increases the CO2 conversion and its energy efficiency almost by a factor of two, compared to the plasma only assisted CO2 dissociation, while the conventional calcined catalysts affect the CO2 conversion rather insignificantly. The conversion of CO2 is found to be about 45% at 70 Torr in pure CO2 with Ar plasma-treated catalyst, having an energy efficiency of 56%. In the case of CO2/H2O mixture, the CO2 conversion efficiency reaches 42% (energy efficiency is 52%) at 60 Torr. The catalyst characterization shows that Ar plasma treatment may result in a higher density of oxygen vacancies and a comparatively uniform distribution of NiO on the TiO2 surface. The dissociative electron attachment of CO2 at the catalyst surface enhanced by the oxygen vacancies and plasma electrons may explain the increase of conversion and energy efficiencies in this case. A mechanism of plasma–catalytic conversion of CO2 at the catalyst surface in CO2/H2O mixture is proposed.
Keywords: CO2 conversion; Plasma-catalysis; CO2/H2O mixture; Microwave discharge; Synergistic effect; Oxygen vacancy;
Efficient removal of chromium from water by Mn3O4@ZnO/Mn3O4 composite under simulated sunlight irradiation: Synergy of photocatalytic reduction and adsorption by Ning Li; Yu Tian; Jianhui Zhao; Jian Zhang; Jun Zhang; Wei Zuo; Yi Ding (126-136).
Display OmittedA novel Mn3O4@ZnO/Mn3O4 composite was designed to remove Cr (VI) and Cr (III) from water by concurrent photocatalysis and adsorption. The Mn3O4@ZnO photocatalyst with core-shell nano-sphere structure, was first fabricated by precisely controlled process using a mild hydrothermal method combined with atomic layer deposition (ALD). The wurtzite ZnO layer was uniformly deposited on hausmannite Mn3O4 surface, which formed a typical II-type heterojunction, separating the photo-generated electron-hole pairs effectively. Hence, rapid Cr (VI) reduction by Mn3O4@ZnO under simulated sunlight irradiation was achieved at 95.3% in 110 min. The pure Mn3O4 as adsorbent could subsequently adsorb the reduced Cr (III) from aqueous solution. Noticeably, the total Cr removal efficiency was enhanced to 92.0% within 70 min by concurrent photocatalysis and adsorption compared to 88.8% even within 120 min in the separate two processes. Mechanism exploration proposed that more active sites on Mn3O4@ZnO surface would be released for continuous photocatalytic reduction of Cr (VI) after the transfer of reduced Cr (III) from Mn3O4@ZnO onto Mn3O4 surface. In addition, the synergy of photocatalysis and adsorption on Cr removal was the strongest at pH = 6.0 and the highest removal efficiency of 96.0% was realized within 70 min. The outstanding synergistic effect of photocatalytic reduction and adsorption makes the innovative Mn3O4@ZnO/Mn3O4 composite a promising candidate for Cr remediation in aquatic environment.
Keywords: Chromium removal; Mn3O4@ZnO/Mn3O4; Atomic layer deposition; Photocatalytic reduction; Adsorption;
A promising N-doped carbon-metal oxide hybrid electrocatalyst derived from crustacean’s shells: Oxygen reduction and oxygen evolution by Gumaa A. El-Nagar; Mohamed A. Hassan; Abdulmonem Fetyan; Manoj Krishna Kayarkatte; Iver Lauermann; Christina Roth (137-147).
Display OmittedThe development of efficient and durable Pt-free catalysts for the oxygen reduction reaction (ORR) is extremely important to realize the world-wide commercialization of the clean energy technologies obstructed by the high cost and scarcity of the Pt-based catalysts. As a potential alternative to such catalysts, this investigation addresses the facile synthesis of an efficient, durable and highly poison-tolerant metal-free N-doped carbon-Nd2O3 hybrid bifunctional electro-catalyst for ORR and water splitting compared to commercial Pt/C catalyst. Chitosan obtained from crustacean’s shells assists to yield a nitrogen-doped graphitic structure with superior activity and durability for ORR. Nd2O3/N―C shows a high tolerance towards crossover of various anodic fuels concurrent with high poisoning tolerance against various hydrocarbon impurities in-situ generated during fuel cell operation. H2-air single cell tests using Nd2O3/N―C as cathode catalyst delivered outstanding power density (∼287 mW cm2) and current density (∼572 mA cm−2) at 0.6 V. The superior electro-catalytic activity and durability of the as-prepared catalysts mainly originates from the synergistic effects between Nd2O3nano particles and the nitrogen-doped graphitic structure. The facile synthesis method and the high performance together with low-cost of our suggested Pt-free catalyst make it as a promising alternative for the commercial Pt/C.
Keywords: Chitosan; N-doped; ORR; OER; Fuel cells; Impurities;
Bi metal sphere/graphene oxide nanohybrids with enhanced direct plasmonic photocatalysis by Zhenyu Wang; Shuai Yan; Yanjuan Sun; Ting Xiong; Fan Dong; Wei Zhang (148-157).
Display OmittedThe Bi metal sphere/graphene oxide (Bi/GO) nanohybrids were firstly synthesized by a simple one-step solvothermal method. Compared with bare Bi spheres, the Bi/GO nanohybrids exhibited highly enhanced and stable direct plasmonic photocatalytic activity towards removal of NO, primarily resulting from the assistance of graphene oxide. The Bi spheres act as antenna for incident light absorption via the SPR effect. The graphene oxide is regarded as an acceptor and transporter of the photogenerated electrons and provides the binding sites for Bi deposition. Furthermore, the related growth and plasmonic photocatalytic mechanisms of Bi/GO nanohybrids system were proposed reasonably. The agreements of the simulation results and experimental study where Bi spheres and Bi/GO nanohybrids were applied as direct plasmonic photocatalysts were discussed for the first time. This work could not only provide new insights into the understanding of the plasmonic effects of Bi spheres but also pave a new way to design direct plasmonic photocatalysts with superior performance.
Keywords: Bi metal sphere; Graphene oxide; Nanohybrids; Direct plasmonic photocatalysis; Mechanism;
Synthesis of MFe2O4 (M = Ni, Co)/BiVO4 film for photolectrochemical hydrogen production activity by Qizhao Wang; Jijuan He; Yanbiao Shi; Shuling Zhang; Tengjiao Niu; Houde She; Yingpu Bi; Ziqiang Lei (158-167).
BiVO4, BiVO4/NiFe2O4 and BiVO4/CoFe2O4 photoelectrodes are used to photoelectrocatalytic water splitting.Display OmittedThe leaf-like structure BiVO4 electrode and MFe2O4/BiVO4 (M = Ni, Co) composite photoelectrodes were prepared by electrochemical deposition, ensuing heating treatment and electrophoretic deposition technology. The characterizations of SEM, XRD and DRS indicated that the BiVO4 derivatives mainly existed in small nanoparticles with monoclinic phase and exhibited stronger light absorption capability than that of pure BiVO4. Hereon, the respective photoelectrochemical (PEC) activities of BiVO4 and its derived composites were systematically studied. The results suggested that the NiFe2O4/BiVO4 and CoFe2O4/BiVO4 not only showed higher photocurrent response values at 1.23 V vs. NHE than pure BiVO4 electrode under visible light illumination, but also played a superior PEC hydrogen evolution performance, which was considered owing to their strong absorption to light, reduction combination of carriers and effective separation of electrons and holes.
Keywords: Fruticose dracaena leaf-like structure; MFe2O4/BiVO4 (M = Ni; Co) composite; PEC performance; Hydrogen production;