Ezhov Roman, Ravari Alireza Karbakhsh, Bury Gabriel, Smith Paul F, Pushkar Yulia
Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA.
Department of Chemistry, Valparaiso University, Valparaiso, IN 46383, USA.
Chem Catal. 2021 Jul 15;1(2):407-422. doi: 10.1016/j.checat.2021.03.013. Epub 2021 May 3.
Catalytic water oxidation is a required process for clean energy production based on the concept of artificial photosynthesis. Here, we provide spectroscopic and computational analysis for the closest known photosystem II analog, [CoO] ([CoOPyAc], Py = pyridine and Ac = CHCOO), which catalyzes electrochemical water oxidation. extended X-ray absorption fine structure detects an ultrashort, Co=O (~1.67 Å) moiety, a crucial intermediate for O-O bond formation. Density function theory analyses show that the intermediate has two Co centers and a Co=O unit of strong radicaloid character sufficient to support a Co=O + HO = Co-OOH + H transition, where the carboxyl ligand accepts the proton and the bridging oxygen stabilizes the peroxide via hydrogen bonding. The proposed water nucleophilic attack mechanism accounts for all prior spectroscopic evidence on the CoO core. Our results are important for the design and development of efficient water oxidation catalysts, which contribute to the ultimate goal of clean energy from artificial photosynthesis.
基于人工光合作用概念，催化水氧化是清洁能源生产所需的过程。在此，我们对已知最接近的光系统II类似物[CoO]（[CoOPyAc]，Py = 吡啶，Ac = CHCOO）进行了光谱和计算分析，该类似物催化电化学水氧化。扩展X射线吸收精细结构检测到一个超短的Co=O（~1.67 Å）部分，这是O-O键形成的关键中间体。密度泛函理论分析表明，该中间体有两个Co中心和一个具有强类自由基特征的Co=O单元，足以支持Co=O + HO = Co-OOH + H转变，其中羧基配体接受质子，桥连氧通过氢键使过氧化物稳定。所提出的水亲核攻击机制解释了以前关于CoO核心的所有光谱证据。我们的结果对于高效水氧化催化剂的设计和开发很重要，这有助于实现人工光合作用产生清洁能源的最终目标。
