High Valence State Sites as Favorable Reductive Centers for High-Current-Density Water Splitting |
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Authors: | Shuo Li Yunxia Liu Kun Feng Chengyu Li Jiabin Xu Cheng Lu Prof Haiping Lin Yong Feng Prof Ding Ma Prof Jun Zhong |
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Institution: | 1. Institute of Functional Nano and Soft Materials Laboratory (FUNSOM), Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123 China;2. Key Laboratory of Special Functional and Smart Polymer Materials of Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an, 710072 China;3. Beijing National Laboratory for Molecular Sciences, New Cornerstone Science Laboratory, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871 China;4. School of Physics and Information Technology, Shaanxi Normal University, Xi'an, 710062 China |
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Abstract: | Electrochemical water splitting is a promising approach for producing sustainable and clean hydrogen. Typically, high valence state sites are favorable for oxidation evolution reaction (OER), while low valence states can facilitate hydrogen evolution reaction (HER). However, here we proposed a high valence state of Co3+ in Ni9.5Co0.5?S?FeOx hybrid as the favorable center for efficient and stable HER, while structural analogues with low chemical states showed much worse performance. As a result, the Ni9.5Co0.5?S?FeOx catalyst could drive alkaline HER with an ultra-low overpotential of 22 mV for 10 mA cm?2, and 175 mV for 1000 mA cm?2 at the industrial temperature of 60 °C, with an excellent stability over 300 h. Moreover, this material could work for both OER and HER, with a low cell voltage being 1.730 V to achieve 1000 mA cm?2 for overall water splitting at 60 °C. X-ray absorption spectroscopy (XAS) clearly identified the high valence Co3+ sites, while in situ XAS during HER and theoretical calculations revealed the favorable electron capture at Co3+ and suitable H adsorption/desorption energy around Co3+, which could accelerate the HER. The understanding of high valence states to drive reductive reactions may pave the way for the rational design of energy-related catalysts. |
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Keywords: | High Current Density High Valence State Hydrogen Evolution Reaction In-Situ X-Ray Absorption Spectroscopy Water Splitting |
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