Tunable Hollow Pt@Ru Dodecahedra via Galvanic Replacement for Efficient Methanol Oxidation

Abstract

Pt-Ru nanocrystals are promising electrocatalysts for methanol oxidation in fuel cells. However, owing to the lattice mismatch and high reduction potential of Ru, the shape-controlled synthesis of Pt-Ru nanocrystals faces great challenges. Herein, we employ a galvanic replacement method to synthesize tunable hollow Pt@Ru dodecahedra via controlling the precursor concentration. Two typical structures, hollow Pt@Ru dodecahedra (h-Pt@Ru) and deformed hollow Pt@Ru dodecahedra (d-Pt@Ru), are obtained to exhibit superior electrocatalytic activities for methanol oxidation. The optimal d-Pt@Ru dodecahedra present a mass activity of 0.80 A mg_Pt^-1 and a specific activity of 1.61 mA cm_Pt^-2, which are 5.25 and 7.78 times higher than those of the commercial Pt/C, respectively. Remarkably, both h-Pt@Ru and d-Pt@Ru show lower oxidation potentials and higher CO-poisoning resistance for methanol oxidation than PtRu nanoparticles (NPs) and commercial Pt/C. This is attributed to the hollow dodecahedron structures with optimal spatial elemental distributions, leading to high utilization of Pt at edges and corners and the exposure of abundant Pt-Ru interfaces. Our strategy offers a facile method to engineer bimetallic metal catalysts regardless of lattice mismatch.