Potential Cycle-Induced Change in the Crystal Structure of a Pt-Skin/PtCo Alloy Nanostructured Electrocatalyst for Fuel Cells

The crystal structure of platinum–cobalt (PtCo) nanoparticles with stabilized Pt-skin layers (PtxAL–PtCo) has been found, for the first time, to change dramatically by conventional potential cycles between 0.05 and 1.0 V versus reversible hydrogen electrode in a N2-saturated 0.1 M HClO4 solution at room temperature. The structure of PtxAL–PtCo, 3% face-centered cubic (fcc) + face-centered tetragonal (fct), was rearranged to single-phase fcc via considerable dissolution of the Co component, resulting in excellent durability while maintaining high activity for the oxygen reduction reaction at practical temperatures for fuel cells.