Hollow core supported Pt monolayer catalysts for oxygen reduction

We synthesized high-activity electrocatalysts for the oxygen reduction reaction comprising a Pt monolayer shell on compact hollow nanoparticles. Pulse electrodeposited Ni nanoparticles were replaced galvanically by Pd and Pd–Au ions to obtain corresponding hollow nanoparticles. Pt monolayer catalysts supported on such hollow cores exhibited total-metal mass activities ranging from 0.41 to 0.57 A mg−1, doubling that of 0.25 A mg−1 for Pt monolayer catalysts on solid Pd cores. We attribute this enhanced activity to the smooth surface morphology and hollow-induced lattice contraction, in addition to the mass-saving geometry of hollow particles.