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Unraveling Sequential Oxidation Kinetics and Determining Roles of Multi-Cobalt Active Sites on Co3O4 Catalyst for Water Oxidation
Journal of the American Chemical Society ( IF 15.0 ) Pub Date : 2023-02-01 , DOI: 10.1021/jacs.2c11508
Wanchao Kang 1, 2 , Ruifang Wei 2 , Heng Yin 2 , Dongfeng Li 2, 3 , Zheng Chen 2 , Qinge Huang 2 , Pengfei Zhang 2 , Huanwang Jing 1 , Xiuli Wang 2 , Can Li 1, 2, 3
Affiliation  

The multi-redox mechanism involving multi-sites has great implications to dictate the catalytic water oxidation. Understanding the sequential dynamics of multi-steps in oxygen evolution reaction (OER) cycles on working catalysts is a highly important but challenging issue. Here, using quasi-operando transient absorption (TA) spectroscopy and a typical photosensitization strategy, we succeeded in resolving the sequential oxidation kinetics involving multi-active sites for water oxidation in OER catalytic cycle, with Co3O4 nanoparticles as model catalysts. When OER initiates from fast oxidation of surface Co2+ ions, both surface Co2+ and Co3+ ions are active sites of the multi-cobalt centers for water oxidation. In the sequential kinetics (Co2+ → Co3+ → Co4+), the key characteristic is fast oxidation and slow consumption for all the cobalt species. Due to this characteristic, the Co4+ intermediate distribution plays a determining role in OER activity and results in the slow overall OER kinetics. These insights shed light on the kinetic understanding of water oxidation on heterogeneous catalysts with multi-sites.

中文翻译:

揭示顺序氧化动力学并确定多钴活性位点对 Co3O4 水氧化催化剂的作用

涉及多位点的多氧化还原机制对决定催化水氧化具有重要意义。了解工作催化剂上析氧反应 (OER) 循环中多步骤的顺序动力学是一个非常重要但具有挑战性的问题。在这里,使用准原位瞬态吸收 (TA) 光谱和典型的光敏化策略,我们成功地解析了涉及 OER 催化循环中水氧化的多活性位点的顺序氧化动力学,其中 Co 3 O 4 纳米粒子作为模型催化剂当 OER 从表面 Co​​ 2+离子的快速氧化开始时,表面 Co​​ 2+和 Co 3+离子是水氧化的多钴中心的活性位点。在顺序动力学(Co 2+ → Co 3+ → Co 4+)中,关键特征是所有钴物种的快速氧化和缓慢消耗。由于这一特性,Co 4+中间体分布在 OER 活性中起着决定性作用,并导致整体 OER 动力学缓慢。这些见解阐明了对具有多位点的多相催化剂进行水氧化的动力学理解。
更新日期:2023-02-01
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