Cu@PtRu Core–Shell Nanostructured Electrocatalysts Anchored on Reduced Graphene Oxide toward Methanol Oxidation

Abstract

This work reports the influence of a reduced graphene oxide (rGO) support on the catalytic performance of Cu@PtRu/rGO electrocatalysts toward methanol oxidation in an acidic medium. These electrocatalysts are synthesized via a two-step reduction method; the first step utilizes ethylene glycol for the reduction of Cu2+ ions, forming Cu/rGO. In the second step, spontaneous redox reactions take place, in a process known as galvanic displacement, where the Pt2+ and Ru3+ species are reduced to form PtRu layers, and the copper is partially oxidized to the solution. Then, the Cu@PtRu/rGO core–shell is produced, comprising Cu in the inner structure (core) and PtRu on the outer part (shell). To compare the catalytic performance of the prepared nanocatalysts (NCs), Pt/C, PtRu/C, and Cu@PtRu/C are also synthesized on Vulcan XC-72R carbon. All catalysts are characterized via X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Cyclic voltammetry (CV) and chronoamperometry (CA) are employed to measure the electrochemical performance. The core–shell/rGO combination is superior in catalytic activity to the traditional Pt/C, PtRu/C, and Cu@PtRu/C catalysts for the methanol oxidation reaction. These results suggest that Cu@PtRu/rGO exhibits a high bulk activity for methanol electrooxidation, a high stability, and a high tolerance to CO poisoning, meaning it is possible to reduce the platinum loading in proton-exchange membrane fuel cells (PEMFCs).