Wang Ping, Le Nghia, McCool John Daniel, Donnadieu Bruno, Erickson Alexander N, Webster Charles Edwin, Zhao Xuan
Department of Chemistry, University of Memphis, Memphis, Tennessee 38152, United States.
Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States.
J Am Chem Soc. 2024 Apr 10;146(14):9493-9498. doi: 10.1021/jacs.3c12928. Epub 2024 Mar 26.
The thermodynamic favorability of an alkaline solution for the oxidation of water suggests the need for developing hydrogen evolution reaction (HER) catalysts that can function in basic aqueous solutions so that both of the half reactions in overall water splitting can occur in mutually compatible solutions. Although photocatalytic HERs have been reported mostly in acidic solutions and a few at basic pHs in mixed organic aqueous solutions, visible-light driven HER catalyzed by molecular metal complexes in purely alkaline aqueous solutions remains largely unexplored. Here, we report a new cobalt complex with a tetrapyridylamine ligand that catalyzes photolytic HER with turnover number up to 218 000 in purely aqueous solutions at pH 9.0. Density functional theory (DFT) calculations suggested a modified electron transfer (E)-proton transfer (C)-electron transfer (E)-proton transfer (C) (mod-ECEC) pathway for hydrogen production from the protonation of Co-H species. The remarkable catalytic activity resulting from subtle structural changes of the ligand scaffold highlights the importance of studying structure-function relationships in molecular catalyst design. Our present work significantly advances the development of a molecular metal catalyst for visible-light driven HER in more challenging alkaline aqueous solutions that holds substantial promise in solar-driven water-splitting systems.
碱性溶液对水氧化反应的热力学有利性表明，需要开发能够在碱性水溶液中发挥作用的析氢反应（HER）催化剂，以便在总体水分解中的两个半反应都能在相互兼容的溶液中发生。尽管光催化析氢反应大多是在酸性溶液中报道的，在碱性pH值的混合有机水溶液中也有少数报道，但在纯碱性水溶液中由分子金属配合物催化的可见光驱动析氢反应在很大程度上仍未得到探索。在此，我们报道了一种带有四吡啶胺配体的新型钴配合物，它在pH 9.0的纯水溶液中催化光解析氢反应，周转数高达218000。密度泛函理论（DFT）计算表明，从Co-H物种的质子化产生氢气存在一种修正的电子转移（E）-质子转移（C）-电子转移（E）-质子转移（C）（mod-ECEC）途径。配体支架的细微结构变化所产生的显著催化活性突出了在分子催化剂设计中研究结构-功能关系的重要性。我们目前的工作极大地推动了在更具挑战性的碱性水溶液中用于可见光驱动析氢反应的分子金属催化剂的开发，这在太阳能驱动的水分解系统中具有巨大的前景。
