Electrocatalysis on Bimetallic Surfaces:  Modifying Catalytic Reactivity for Oxygen Reduction by Voltammetric Surface Dealloying

We report a synthetic electrochemical strategy to deliberately modify the catalytic reactivity of Pt bimetallic surfaces. The strategy consists of voltammetric surface dealloying of the non-noble constituent from Pt-poor bimetallic precursor compounds. We exemplify this method by dealloying carbon-supported Pt25Cu75 alloy nanoparticle precursors and testing the resulting active catalyst phase for the oxygen reduction reaction (ORR). We show that dealloyed Pt−Cu electrocatalysts exhibit an extraordinary increase in intrinsic reactivity of 4−6 times as compared to pure Pt electrocatalysts. Our results indicate that electrochemical treatment of the alloy precursors selectively dissolves Cu near the particle…