Electrochemical Dealloying of Ni-Rich Pt–Ni Nanoparticle Network for Robust Oxygen-Reduction Electrocatalysts
Jaeyoung Yoo, Youngtae Park, Jungwoo Choi, JeongHan Roh, Kihyun Shin, Hyun‐Seok Cho, EunAe Cho, Changsoo Lee, Hyuck Mo Lee
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.