Interfacial Engineering of Ni/V2O3 Heterostructure Catalyst for Boosting Hydrogen Oxidation Reaction in Alkaline Electrolytes

Alkaline fuel cells can permit the adoption of platinum group metal-free (PGM-free) catalysts and cheap bipolar plates, thus further lowering the cost. With the exploration of PGM-free hydrogen oxidation reaction (HOR) catalysts, nickel-based compounds have been considered as the most promising HOR catalysts in alkali. Here we report an interfacial engineering through the formation of nickel-vanadium oxide (Ni/V₂O₃) heterostructures to activate Ni for efficient HOR catalysis in alkali. The strong electron transfer from Ni to V₂O₃ could modulate the electronic structure of Ni sites. The optimal Ni/V₂O₃ catalyst exhibits a high intrinsic activity of 0.038 mA cm⁻² and outstanding stability. Experimental and theoretical studies reveal that Ni/V₂O₃ interface as the active sites can enable to optimize the hydrogen and hydroxyl bindings, as well as protect metallic Ni from extensive oxidation, thus achieving the notable activity and durability.     

Pt/MOx-SiO2 (M=Ce,Zr, Al)催化剂对CO和C3H8氧化性能的影响

采用共沉淀法制备质量比为1:1的MOx-SiO2(M=Ce,Zr,Al)复合氧化物,以此为载体采用浸渍法制备了铂基氧化型催化剂.考察了该系列催化剂在模拟柴油车尾气条件下,经SO2硫化前后对C3H8和CO的氧化性能.用X射线衍射(XRD)、低温N2吸附-脱附、氨气/氧气/二氧化碳程序升温脱附(NH3/O2/CO2-TPD)和X射线光电子能谱(XPS)等手段进行了表征.NH3-TPD证实催化剂表面存在多种酸中心,硫化后催化剂表面中强酸中心增多.O2-TPD证实催化剂表面存在α和β氧物种,硫化后催化剂表面氧脱附量减少.其中Pt/Al2O3-SiO2表面酸性最弱和表面氧脱附量最大.XPS结果表明新鲜催化剂经硫化后会使催化剂表面Pt的结合能降低.活性测试结果表明,三种催化剂对CO和C3H8的催化氧化活性均较好,其中Pt/ZrO2-SiO2抗SO2中毒性能最佳,具有良好的应用前景.     

Role of Bismuth Oxide in Bi-MCo2O4（M=Co,Ni,Cu,Zn） Catalysts for Wet Air Oxidation of Acetic Acid

Two series of cobalt (Ⅲ)-containing spinel catalysts were prepared by the decomposition of the corre-sponding nitrates. The catalysts doped with bismuth oxide exhibit a higher activity in the wet air oxidation ofacetic acid than those without dopant bismuth oxide. The catalysts were investigated by XRD, TEM, ESR,UV-DRS and XPS, and the interaction between Co and Bi was studied as well. It has been found that nano-sized bismuth oxide is paved on the surface of cobalt spinel crystal and the structures of cobalt(Ⅲ)-containingspinel are still maintained. The shift of the binding energy of Bi4/7/2 is related to the catalytic activity of thesecatalysts doped with bismuth oxide.     

An Efficient Catalytic Procedure for the Selective Oxidation of Sulfides to Sulfoxides by Citric Acid/Al(NO3)3.9H2O/MBr Under Mild and Heterogeneous Conditions

A wide range of aliphatic or aromatic sulfides are selectively oxidized to the corresponding sulfoxides using Al(NO₃)₃.9H₂O, citric acid and a catalytic amount of KBr or NaBr in the presence of wet SiO₂ (50% w/w)in CH₂Cl₂ under mild and heterogeneous conditions in good to high yields.     

Oxidation of o‐phenylenediamine to 2,3‐diaminophenazine in the presence of cubic ferrites MFe2O4 (M = Mn,Co, Ni,Zn) and the application in colorimetric detection of H2O2

Metal ferrites nanocrystallites, MFe₂O₄ (M = Mn, Co, Ni, Zn) were prepared by coprecipitation method and characterized by a combination of physico‐chemical and spectroscopic techniques. MFe₂O₄ nanoparticles having particle size in the range 10–35 nm were tested as catalysts in the oxidation of o‐phenylenediamine (OPD) to 2,3–diaminophenazine (DAP) using hydrogen peroxide as oxidant at room temperature. Kinetic data was collected for the catalytic oxidation of OPD to DAP by monitoring the UV–vis absorbance at 415 nm and fit well to the Michaelis–Menten model yielding kinetic parameters K_m (Michaelis–Menten constant) and V_max (maximum rate of reaction). MnFe₂O₄ nanoparticles provide the highest catalytic activity in the oxidation of OPD to DAP at room temperature. A colorimetric method was developed based on the MnFe₂O₄/OPD system for the detection of H₂O₂ in reaction solution. The method has a detection limit of 30 μM for H₂O₂ and wide linear range.     

Novel catalyst system of MCl2/FeCl3·6H2O/PPh3 (M = Ni,Co, or Mn) for the atom transfer radical polymerization of methyl methacrylate

MCl₂ (M = Ni, Co, Sn, or Mn) and PPh₃ together acted as a catalyst for the radical polymerization of methyl methacrylate (MMA) in the presence of ethyl 2‐bromoisobutyrate as an initiator. The four systems all led to conventional radical polymerizations, which yielded polymers with a weight‐average molecular weight/number‐average molecular weight (M_w/M_n) ratio greater than 2.0 and became well controlled when a certain amount of FeCl₃·6H₂O was added. The polymerizations of MMA catalyzed by these four FeCl₃‐modified catalyst systems provided well‐defined polymers with low polydispersities (M_w/M_n < 1.28). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2625–2631, 2005