Zhang Rongrong, Pan Lun, Guo Beibei, Huang Zhen-Feng, Chen Zhongxin, Wang Li, Zhang Xiangwen, Guo Zhiying, Xu Wei, Loh Kian Ping, Zou Ji-Jun
Key Laboratory for Green Chemical Technology of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China.
J Am Chem Soc. 2023 Feb 1;145(4):2271-2281. doi: 10.1021/jacs.2c10515. Epub 2023 Jan 18.
Dynamic reconstruction of catalyst active sites is particularly important for metal oxide-catalyzed oxygen evolution reaction (OER). However, the mechanism of how vacancy-induced reconstruction aids OER remains ambiguous. Here, we use CoO with Co or O vacancies to uncover the effects of different defects in the reconstruction process and the active motifs relevant to alkaline OER. Combining in situ characterization and theoretical calculations, we found that cobalt oxides are converted to an amorphous [Co(OH)] intermediate state, and then the mismatched rates of *OH adsorption and deprotonation lead to irreversible catalyst reconstruction. The stronger *OH adsorption but weaker deprotonation induced by O defects provides the driving force for reconstruction, while Co defects favor dehydrogenation and reduce the reconstruction rate. Importantly, both O and Co defects trigger highly OER-active bridge Co sites in reconstructed catalysts, of which Co defects induce a short Co-Co distance (3.38 Å) under compressive lattice stress and show the best OER activity (η of 262 mV), superior to reconstructed oxygen-defected CoO-V (η of 300 mV) and defect-free CoO (η of 320 mV). This work highlights that engineering defect-dependent reconstruction may provide a rational route for electrocatalyst design in energy-related applications.
催化剂活性位点的动态重构对于金属氧化物催化的析氧反应（OER）尤为重要。然而，空位诱导重构促进OER的机制仍不明确。在此，我们使用具有Co或O空位的CoO来揭示重构过程中不同缺陷的影响以及与碱性OER相关的活性基序。结合原位表征和理论计算，我们发现氧化钴会转变为非晶态的[Co(OH)]中间态，然后OH吸附和解质子化的不匹配速率导致催化剂发生不可逆重构。由O缺陷诱导的更强的OH吸附但更弱的去质子化提供了重构的驱动力，而Co缺陷有利于脱氢并降低重构速率。重要的是，O和Co缺陷都会在重构催化剂中触发高OER活性的桥式Co位点，其中Co缺陷在压缩晶格应力下诱导出短的Co-Co距离（3.38 Å）并表现出最佳的OER活性（过电位为262 mV），优于重构的氧缺陷CoO-V（过电位为300 mV）和无缺陷的CoO（过电位为320 mV）。这项工作突出表明，基于缺陷的工程重构可能为能源相关应用中的电催化剂设计提供一条合理途径。
