Reconstruction of High Entropy Alloys on a Metal–Organic Framework Approaching Active Oxygen Reduction Electrocatalysts

• Published in: Nano letters 2024-06, Vol.24 (24), p.7293-7301
• Main Authors: Liang, Jing, Ma, Yanling, Li, Yanjie, Zhang, Wencong, Hu, Hao, Su, Jie, Yao, Zhenpeng, Gao, Wenpei, Shang, Wen, Deng, Tao, Wu, Jianbo
• Format: Article
• Language: English
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.4c01278

High-entropy alloys (HEAs) have garnered considerable attention as promising nanocatalysts for effectively utilizing Pt in catalysis toward oxygen reduction reactions due to their unique properties. Nonetheless, there is a relative dearth of attention regarding the structural evolution of HEAs in response to electrochemical conditions. In this work, we propose a thermal reduction method to synthesize high entropy nanoparticles by leveraging the confinement effect and abundant nitrogen-anchored sites provided by pyrolyzed metal–organic frameworks (MOFs). Notably, the prepared catalysts exhibit enhanced activity accompanied by structural reconstruction during electrochemical activation, approaching 1 order of magnitude higher mass activity compared to Pt/C in oxygen reduction. Atomic-scale structural characterization reveals that abundant defects and single atoms are formed during the activation process, contributing to a significant boost in the catalytic performance for oxygen reduction reactions. This study provides deep insights into surface reconstruction engineering during electrochemical operations, with practical implications for fuel cell applications.