Wang Ping, Liang Guangchao, Smith Noah, Hill Kyra, Donnadieu Bruno, Webster Charles Edwin, Zhao Xuan
Department of Chemistry, The University of Memphis, Memphis, TN, 38152, USA.
Department of Chemistry, Mississippi State University, Mississippi State, MS, 39762, USA.
Angew Chem Int Ed Engl. 2020 Jul 27;59(31):12694-12697. doi: 10.1002/anie.202002640. Epub 2020 May 19.
To explore the structure-function relationships of cobalt complexes in the catalytic hydrogen evolution reaction (HER), we studied the substitution of a tertiary amine with a softer pyridine group and the inclusion of a conjugated bpy unit in a Co complex with a new pentadentate ligand, 6-[6-(1,1-di-pyridin-2-yl-ethyl)-pyridin-2-ylmethyl]-[2,2']bipyridinyl (Py3Me-Bpy). These modifications resulted in significantly improved stability and activity in both electro- and photocatalytic HER in neutral water. Co(Py3Me-Bpy)(OH ) catalyzes the electrolytic HER at -1.3 V (vs. SHE) for 20 hours with a turnover number (TON) of 266 300, and photolytic HER for two days with a TON of 15 000 in pH 7 aqueous solutions. The softer ligand scaffold possibly provides increased stability towards the intermediate Co species. DFT calculations demonstrate that HER occurs through a general electron transfer/proton transfer/electron transfer/proton transfer pathway, with H released from the protonation of Co -H species.
为了探索钴配合物在催化析氢反应（HER）中的结构-功能关系，我们研究了用较软的吡啶基团取代叔胺，并在具有新型五齿配体6-[6-(1,1-二吡啶-2-基-乙基)-吡啶-2-基甲基]-[2,2']联吡啶基（Py3Me-Bpy）的钴配合物中引入共轭的bpy单元。这些修饰显著提高了在中性水中电催化和光催化HER的稳定性和活性。Co(Py3Me-Bpy)(OH)在-1.3 V（相对于标准氢电极）下催化电解HER 20小时，周转数（TON）为266300，在pH 7的水溶液中光催化HER两天，TON为15000。较软的配体骨架可能为中间钴物种提供了更高的稳定性。密度泛函理论计算表明，HER通过一般的电子转移/质子转移/电子转移/质子转移途径发生，H从Co-H物种的质子化中释放。
