Enhancing the Electrocatalytic Activity of Pd/M (M = Ni, Mn) Nanoparticles for the Oxygen Reduction Reaction in Alkaline Media through Electrochemical Dealloying

We have developed a facile and effective electrochemical dealloying strategy to enhance the electrocatalytic activity of Pd/M (M = Ni, Mn) nanoparticles for the oxygen reduction reaction (ORR) in alkaline media. The enhancement arises from the higher atomic concentration of electrochemically active Pd exposed on the surface of the nanoparticles as a result of the electrochemical dealloying process, which was verified by electron energy loss spectroscopy elemental mapping, X-ray photoelectron spectroscopy, and CO stripping. These dealloyed catalysts also showed a negligible decrease in the ORR activity after 4000 potential cycles in alkaline media. In addition, after the degradation that resulted from extended potential cycles in alkaline media, the ORR activity of the catalysts could be restored by repeating the dealloying procedures, with only a 14 mV decrease in the half-wave potential after 16,000 cycles for dealloyed PdNi/C. Similar results were obtained for PdMn/C. These findings provide insights for the rational design of the composition and structure of electrocatalysts with higher atomic utilization of active materials and enhanced electrocatalytic activity, based on postsynthesis modification methods.