Platinum-Based Nanowires as Active Catalysts toward Oxygen Reduction Reaction: In Situ Observation of Surface-Diffusion-Assisted Solid-State Oriented Attachment

Yanling Ma(1), Wenpei Gao(2), Hao Shan(1), Wenlong Chen(1), Wen Shang(1), Peng Tao(1), Chengyi Song(1), Chris Addiego(3), Tao Deng(1), Xiaoqing Pan(2,3), and Jianbo Wu(1), 2017

Abstract

Facile fabrication of advanced catalysts toward oxygen reduction reaction with improving activity and stability is significant for proton‐exchange membrane fuel cells. Based on a generic solid‐state reaction, this study reports a modified hydrogen‐assisted, gas‐phase synthesis for facile, scalable production of surfactant‐free, thin, platinum‐based nanowire‐network electrocatalysts. The free‐standing platinum and platinum–nickel alloy nanowires show improvements of up to 5.1 times and 10.9 times for mass activity with a minimum 2.6% loss after an accelerated durability test for 10k cycles; 8.5 times and 13.8 times for specific activity, respectively, compared to commercial Pt/C catalyst. In addition, combined with a wet impregnation method, different substrate‐materials‐supported platinum‐based nanowires are obtained, which paves the way to practical application as a next‐generation supported catalyst to replace Pt/C. The growth stages and formation mechanism are investigated by an in situ transmission electron microscopy study. It reveals that the free‐standing platinum nanowires form in the solid state via metal‐surface‐diffusion‐assisted oriented attachment of individual nanoparticles, and the interaction with gas molecules plays a critical role, which may represent a gas‐molecular‐adsorbate‐modified growth in catalyst preparation. Keywords:  in situ TEM, oriented attachment, oxygen reduction reaction, platinum‐based nanowires, solid‐state reaction

Impact Statement

The authors studied the growth stages and formation of platinum-based nanowires for PEM fuel cells. They show very good mass activity results for their nanowires and reveal the method in which these nanowires form. These data show great promise for platnium nanowires for fuel cells due to their surfactant-free sythesis and high activity.