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Deciphering the Dynamic Structure Evolution of Fe- and Ni-Codoped CoS2 for Enhanced Water Oxidation

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journal contribution
posted on 2022-03-10, 18:35 authored by Wenfeng Peng, Amol Deshmukh, Ning Chen, Zhengxing Lv, Shijing Zhao, Jiong Li, Bingmin Yan, Xiang Gao, Lu Shang, Yutong Gong, Lailei Wu, Mingyang Chen, Tierui Zhang, Huiyang Gou
Multimetal doping is a promising strategy to achieve high-performance electrocatalysts for the oxygen evolution reaction (OER) due to synergistic effects; however, understanding the dynamic structure evolution and clarifying the catalytic mechanism of each individual doping metal in multimetal-based electrocatalysts remain elusive. Here, we report the synthesis of homogeneous single-metal and bimetal doping sulfides with a pyrite structure for OER catalysts via a high-pressure and high-temperature (HPHT) technique; operando Raman and X-ray absorption spectroscopy (XAS) studies are performed to capture the dynamic evolution during the OER process. Our results find that an Fe- and Ni-codoped CoS2 electrocatalyst exhibits significantly improved OER activity with an overpotential of 242 (295) mV at 10 (100) mA cm–2 and robust stability over 500 h in an alkaline medium. Operando analysis reveals that Fe and Ni incorporations not only expedite the dynamic response of self-reconstructions of the Fe,Ni-CoS2 surface but also accelerate the oxidation of Co and Fe into high-valence oxyhydroxides while suppressing nickel oxidation to form Ni­(OH)2 for optimized activity and robust stability. This finding provides a fundamental understanding of the composition design, dynamic reaction pathways, and controlling principle for highly active multimetal-based OER catalysts.