Electrochemical Dealloying of Ni-Rich Pt-Ni Nanoparticle Network for Robust Oxygen-Reduction Electrocatalysts

Abstract

Increasing the electrochemically active surface area (ECSA) and alloying Pt with transition metals (TMs) are well-known strategies for enhancing the oxygen reduction reaction (ORR) catalytic activities. Herein, we introduce a strategy to produce highly active ORR electrocatalysts with a large ECSA using an electrochemical dealloying process involving leaching of Ni from a Ni-rich Pt-Ni nanoparticle network. The dealloying process yielded a dealloyed Pt-Ni nanoparticle network with rugged surfaces from the Ni-rich Pt-Ni nanoparticle network, resulting in a large ECSA. We also increased the mass activity and utilization efficiency of Pt by modulating the interactions between Pt and Ni. The dealloyed nanoparticle network exhibited a high ORR mass activity, six times higher than that of commercial Pt/C. Moreover, the dealloyed Pt-Ni nanoparticle network exhibited better catalytic stability than the Pt/C after 10000 potential cycles, even without carbon support. The reduced binding energy of the O intermediate due to the effects of Ni (ligand and strain effects) enhanced the ORR activity of the dealloyed nanoparticle network, according to the results of a mechanistic study performed using density functional theory. This study opens new avenues for designing TM-alloy catalysts with high ORR activity for various applications.