碳纳米粒子支撑的钯纳米催化剂在甲酸氧化中的电催化活性(英文)

Electrocatalytic Activity of Palladium Nanocatalysts Supported on Carbon Nanoparticles in Formic Acid Oxidation

采用化学还原法制备了碳纳米粒子支撑的钯纳米结构（Pd-CNP）.透射电镜表征显示在Pd-CNP纳米复合物中,金属Pd呈菜花状结构,粒径约20~30 nm.它们由许多更小的Pd纳米粒子（3~8 nm）组成.电化学研究表明,Pd-CNP的电化学活性面积比商业Pd黑低40%,可能原因是部分Pd表面被一层碳纳米粒子覆盖,但其对甲酸氧化却表现出更好的电催化活性,质量比活性和面积比活性都比Pd黑高几倍.催化活性增强的原因可能是碳纳米粒子支撑的Pd纳米结构具有特殊的层次化结构,可以形成更多的活性位,以及表面位更利于反应进行.

Palladium nanostructures were deposited onto carbon nanoparticle surface by a chemical reduction method. Transmission electron microscopic studies showed that whereas the resulting metal-carbon （Pd-CNP） nanocomposites exhibited a diameter of 20 to 30 nm, the metal components actually showed a cauliflower-like surface morphology that consisted of numerous smaller Pd nanoparticles （3 to 8 run）. Electrochemical studies showed that the effective surface area of the Pd-CNP nanoparticles was about 40% less than that of Pd black, possibly because the Pd nanoparticles were coated with a layer of carbon nanoparticles; yet, the Pd-CNP nanocomposites exhibited marked enhancement of the electrocatalytic activity in formic acid oxidation, as compared to that of Pd black. In fact, the mass- and surface-specific activities of the former were about three times higher than those of the latter. This improvement was likely a result of the enhanced accessibility of the Pd catalyst surface and the formation of abundant active sites of Pd on the carbon nanoparticle surface due to the hierarchical structure of the metal nanocatalysts.