Effect of Core Composition in AuxCuy@Pt/C for the Methanol Oxidation Reaction

摘要

In this work, the effect of core composition in AuxCuy@Pt/C core@shell catalysts for methanol oxidation is investigated. The catalysts were prepared varying Au:Cu atomic percentage (i.e., 100:0, 75:25, 50:50, 25:75, and 0:100 %) while maintaining Pt constant. The average particle size of every sample was obtained from STEM measurements, while XRD measurements allowed to determining their crystal structure; in all cases, a FCC crystal structure was obtained. From chronoamperometry, it was found that the values of steady-state current density (I (ss)) increased with the gold content in the core, i.e., I (ss) values are 2.52, 1.86, 1.18, 0.34, and 0.18 mA cm(-2) for Au100Cu0@Pt, Au75Cu25@Pt, Au50Cu50@Pt, Au25Cu75@Pt, and Au0Cu100@Pt, respectively. Similar results were obtained by using cyclic voltammetry, where the value of the peak current density increased as the gold content in the core increased: this behavior is associated to the modified electrochemical activity of Pt (shell) caused by the core composition (AuxCuy).