Synthesis of hollow structured PtNi/Pt core/shell and Pt-only nanoparticles via galvanic displacement and selective etching for efficient oxygen reduction reaction

Abstract

This study uses a simple galvanic displacement-acid etching method for synthesizing PtNi nanoparticles with different morphologies and surface properties. Core/shell structured Ni/PtNi nanoparticles were prepared from nickel nanoparticles subjected to a galvanic displacement reaction with Pt ions. By controlling the dealloying conditions, hollow PtNi/Pt core/shell (H-PtNi/Pt) and Pt-only (H-Pt) nanoparticles could be formed. The H-PtNi/Pt catalyst showed the highest oxygen reduction reaction (ORR) mass and specific activities (0.8 A mg = 1Pt and 1520 lA cm = 2 Pt at 0.9 VRHE), which were 3.33- and 5.67-times higher than those of commercial Pt/C. It revealed that forming a PtNi/Pt core/shell structure with a hollow morphology plays an important role for enhancing ORR activity. The H-PtNi/Pt catalyst also showed a very low degradation in specific activity of less than 1% after extensive potential cycling (10,000 cycles) due to the stable platinum outer layer covering the hollow PtNi alloy structure. (c) 2022 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.