Structural characterizations of Cu3Pt electrocatalyst featuring Pt-rich surface layers synthesized via mechanical alloying and selective dissolution routes

Abstract

We demonstrate a selective electrochemical dissolution route to prepare Cu3Pt catalysts featuring Pt-rich surface layers (Cu3Pt-Pt rich surface) from mechanically alloyed Cu3Pt. These catalysts were investigated by X-ray diffraction and X-ray absorption spectroscopy, and were subjected to electrochemical analyses to evaluate their catalytic properties. With appropriate anodization, Cu3Pt entered an oxygen-evolving regime where the corrosive dissolution of Cu dominated the reaction. Selective dissolution was carried out to prepare Pt-rich layers at the surface, while Cu3Pt was left unreacted at the core. An increase in the anodization duration modified the sample morphology, with the redistribution of Pt atoms to thicken the surface layers. A charge transfer from Pt to Cu accompanied the structural transition from Cu3Pt to Cu3Pt-Pt rich surface upon selective dissolution, rendering the sample to be electronically similar to a metal Pt. However, compared to the metal Pt and conventional Pt-based catalysts, the proposed structure is a more economical catalyst for direct methanol fuel cell, with less need of Pt in raw material but increased electrochemical surface area by exposing enormous Pt at the surface with an increase in the anodization duration. (C) 2012 Elsevier B.V. All rights reserved.