Study of electrocatalysts for oxygen reduction based on electroconducting polymer and nickel

The properties and electrocatalytic activity were studied of composite carbon‐supported materials based on heterocyclic polymer and nickel, in particular carbon/polyaniline/nickel, carbon/polypyrrole/nickel, carbon/poly(3‐methylthiophene)/nickel, as well as their precursors, carbon/polyaniline, carbon/polypyrrole, and carbon/poly(3‐methylthiophene). The materials were characterized by means of thermogravimetric analysis (TGA), scanning electron microscopy (SEM), EDAX, and electrochemical methods, such as cyclic voltammetry and linear voltammetry using RDE. SEM show porous materials, with a particle size of around 0.3 μm. It was found that in nickel‐modified catalysts between 5 and 6 wt % of nickel is obtained. TGA and FTIR show that the modification with nickel alters the polymer bonds. Curves from cyclic voltammetry show cathodic peaks corresponding to the oxygen reduction reaction (ORR) in all materials, occurring at relatively low potentials. Based on the potential range for ORR as well as kinetic parameters obtained from linear voltammetry using RDE, it was concluded that C‐Ppy‐Ni shows the best performance for ORR in acidic medium. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

新型包覆碳化钨载体负载Pd催化剂的性能

以Vulcan XC-72R活性碳作为碳源,采用高温热处理还原法,在活性碳表面原位还原钨酸铵,形成表面包覆钨的碳化物结构的载体。通过BET等当钨酸铵用量适宜时,形成的钨的碳化物的平均孔径较大,较大介孔所占比例较大,以其为载体制备的Pd催化剂Pd/WC-2其电荷传递阻抗和扩散阻抗都较小。催化剂Pd/WC-2对甲酸的氧化不但具有较高的活性,同时也具有很好的稳定性。     

Electrochemistry of Single Nanoparticles via Electrocatalytic Amplification

Recent experiments on the observation of collisions of single nanoparticles (NPs) with an electrode through amplification of the current by electrocatalysis are described. Systems in which the particles adhere to the electrode upon collision produce a step and staircase response, while those in which particles only interact for a short time with the electrode produce a spike or blip, with little change in the steady state current. Examples of both behaviors, e. g., Pt NPs on a Au electrode for hydrazine oxidation (staircase response) and IrO_x NPs on a Pt electrode for water oxidation (blip response) are shown. Controlling the nature of the electrode surface is important in generating useful responses, for example, in the case of gold NPs on an oxidized Pt electrode for borohydride oxidation.     

Polyaniline/carbon black composite as Pt electrocatalyst supports for methanol oxidation: Synthesis and characterization

Core/shell composites of polyaniline (PANI) and Vulcan XC‐72 Carbon (VC), in which the carbon represents the core and PANI forms the shell, were synthesized by in situ chemical oxidation polymerization. Platinum (Pt) particles were then deposited on the PANI/VC composites by chemical reduction method. The highest conductivity is obtained when a mass ratio of PANI/VC equals to 0.28, as proved by Fourier transform infrared spectra. And it is also proved that there are some reactions happened between PANI and VC. Scanning electron microscope, transmission electron microscope, and X‐ray diffraction measurements were performed to analyze their structure and surface morphology. It has been observed that the Pt particles are smaller in size and more uniformly distributed on these composite supports than on pure VC supports, considered as a reference. Methanol oxidation performed on the electrode modified by such a composite catalyst has been measured by cyclic voltammogram focusing on the attenuation of methanol oxidation current after 200 cycles. The attenuation degree for the composite catalyst is only one‐third of the one measured for a simple Pt/VC catalyst. It is proved that the composite catalyst better resist carbon monoxide poisoning in comparison with the Pt/VC catalyst, which may be due to the synergetic effects between the composite support and the Pt catalyst. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

几种电化学法处理苯酚废水对比试验研究

以苯酚模拟废水为研究对象,对几种电化学法处理苯酚废水的效果进行对比研究,采用正交试验对pH值、电解电压、电解质浓度,电解时间等4个因素对苯酚去除率的影响进行分析,并确定最佳反应条件。试验结果表明,电催化氧化法处理苯酚废水的最佳反应条件为:pH值为6,电解电压为9 V,电解质的质量浓度为20 g/L,电解时间为120 min;电-Fenton法处理苯酚废水的最佳反应条件为:pH值为3,电解电压为9 V,电解质的质量浓度为20 g/L,电解时间为120 min;在此基础上,三维电极法最佳活性炭投加量为150 g/L。4种电化学法处理苯酚废水效果的优劣顺序依次为:三维电极与电-Fenton耦合法三维电极法电-Fenton法电催化氧化法。     

Platinum-nickel bimetallic catalyst doped with rare earth for enhancing methanol electrocatalytic oxidation reaction

Platinum (Pt) is often used as anodic catalyst for direct methanol fuel cell (DMFC). However, platinum is difficult to achieve large-scale application because of its low stability and high cost. In this work, the electrocatalytic activity and stability of the Pt-based catalyst for methanol oxidation (MOR) are significantly improved by adding Ce and Ni to the catalyst. Additionally, the rare earth element-Pr (Dy) is also chosen to be added into the catalysts for comparison. A series of PtMNi (M = Ce, Pr, Dy) catalysts are prepared by impregnation and galvanic replacement reaction methods using carbon black as support. The electrocatalytic mass activity of PtCeNi/C, PtDyNi/C, PtPrNi/C and Pt/C is 3.92, 1.86, 1.69 and 0.8 A mg_Pt⁻¹, respectively. The mass activity of these the above four catalysts after stability measurement is 3.14, 1.49, 1.27 and 0.72 A mg_Pt⁻¹. Among them, PtCeNi/C has the highest catalytic activity. These as-prepared catalysts are also characterized by various analyzing techniques, such as TEM, HRTEM, XRD, XPS, ICP-OES, STEM, STEM-EDS elemental mapping and line-scanning etc. It shows that PtCeNi/C exhibits best catalytic activity (3.92 A mg_Pt⁻¹) among the as-obtained catalysts, 4.9 times higher than that of commercial Pt/C (0.8 A mg_Pt⁻¹). PtCeNi/C is also with excellent anti-CO poisoning ability. The outstanding catalytic performance of PtCeNi/C for the MOR is mainly attributable to uniform-sized PtCeNi nanoparticles, uniform Ni, Ce and Pt element distribution, and electron interaction among Pt-, Ni- and Ce-related species (electron transferring from Pt to CeO₂).     

Virtual pressure and virtual fugacity in catalysis and electrocatalysis

The generalized De Donder equation and the generalized Butler-Volmer equation can be used to understand and calculate so-called virtual pressure or virtual fugacity of reactants or products in catalytic and electrocatalytic cycles respectively. This illustrates the usefulness of general relations between kinetics and thermodynamics in sub-fields of catalysis that differ in their methodology.     

碳纳米管担载纳米银及其电催化甲醇氧化的研究

以水溶性离聚物聚（苯乙烯磺酸钠-co-丙烯酸）（PSA）接枝多壁碳纳米管为模板,制备了碳纳米管担载纳米银（AgNP@MWNT）,研究了在碱性条件下对甲醇氧化的电催化作用。结果表明接枝在MWNT表面的离聚物PSA有效地控制了AgNP在MWNT表面以2～4nm的尺寸均匀担载,促进了AgNP与MWNT之间的界面相互作用。制备的Ag@MWNT在水中能够稳定地均匀分散,在碱性条件下可有效地电催化甲醇氧化,抗甲醇中毒性能良好。     

膜技术处理印染废水研究进展

介绍了膜分离及集成技术在印染水处理中的应用,分析了膜污染存在的原因及解决膜污染问题的研究现状,重点介绍具有自清洁功能的电催化膜及其抗污染机理.最新结果显示,电催化膜利用膜分离与间接氧化协同作用能够实现印染废水高效降解,是一种绿色环保的污水处理新技术,具有广阔的应用前景.开发具有抗污染、长寿命、高通量的膜材料以及集成技术...     

甲醛在nano-Pt/GC电极上的电催化氧化研究

应用循环伏安法制备了nano-Pt/GC电极,并用SEM和电极在H2SO4中的循环伏安曲线对其进行了表征。结果表明,该方法制备的电极表面铂粒子分布较为均匀,粒径大小约为140nm,电极具有较大比表面积。电化学实验表明,该电极对甲醛电氧化的催化活性明显好于铂片电极。修饰电极的催化活性与铂粒子的沉积条件有关,铂微粒在电极表面的最佳沉积条件为循环次数100次和沉积速度5mV/s。