纳米晶体在电催化甲酸氧化反应中的形貌效应
摘要
Palladium nanocrystals with various shapes and sizes were controllably synthesized by altering oxidative etching and reaction kinetics in the presence of appropriate metal precursors, reducing agents, stabilizers and capping agents, based on our previous works. Upon cleaning nanoparticles and assembling them onto electrodes, we systematically investigated the relationship between nanocrystal structures and catalytic performance in the oxidation of formic acid. It demonstrates that the maximum current densities of Pd nanocrystals increase in the order of nanoctahedra < nanowires < nanocubes < nanotapers < concave nanocubes. The onset potentials of all the samples are below 0.2 V. The results prove that the electrocatalytic performance of Pd nanocrystals is not significantly dependent on their sizes after normalized by active surface area. Instead, the catalytic activity is mainly determined by surface structures: the activities of various Pd facets in the oxidation of formic acid should be in the order of {111} < {100} < high-index facets. Among various Pd nanostructures, concave nanocubes and nanotapers exhibit much better electrocatalytic performance.