Electrodeposition of Pt–Rh Trioctahedral Nanocrystals for the Oxidation Reactions of Methanol and Ethanol

The bimetallic nanoparticles of Pt-group metals surrounded by high-index facets have both alloying electronic effects and surface structure effects and are promising catalysts for fuel cells. In this work, the electrochemical square wave potential method was used to prepare Pt–Rh trioctahedral nanocrystals with {441} high-index facets without introducing any surfactants. The structures of the nanocrystals were checked carefully and the effects of parameters such as growth/etching potential, frequency, concentrations of precursors, etc., were also investigated systematically. The balance between etching and growth was found to be crucial in the successful synthesis of Pt–Rh trioctahedral nanocrystals. Due to the unique surface structure as well as alloy effect, the prepared Pt–Rh trioctahedral nanocrystals exhibited excellent electrocatalytic activities for methanol and ethanol oxidation reactions and were 5.3 times and 3.8 times more active than those of commercial Pt/C catalysts, respectively. In addition, the Pt–Rh trioctahedral nanocrystals as-synthesized showed stability much better than that of commercial Pt/C, which was critical for practical application.