Roy Souvik, Huang Zhehao, Bhunia Asamanjoy, Castner Ashleigh, Gupta Arvind K, Zou Xiaodong, Ott Sascha
Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523, 751 20 Uppsala , Sweden.
Berzelii Centre EXSELENT on Porous Materials, Department of Materials and Environmental Chemistry , Stockholm University , 106 91 Stockholm , Sweden.
J Am Chem Soc. 2019 Oct 9;141(40):15942-15950. doi: 10.1021/jacs.9b07084. Epub 2019 Sep 25.
Molecular hydrogen evolution catalysts (HECs) are synthetically tunable and often exhibit high activity, but they are also hampered by stability concerns and practical limitations associated with their use in the homogeneous phase. Their incorporation as integral linker units in metal-organic frameworks (MOFs) can remedy these shortcomings. Moreover, the extended three-dimensional structure of MOFs gives rise to high catalyst loadings per geometric surface area. Herein, we report a new MOF that exclusively consists of cobaloximes, a widely studied HEC, that act as metallo-linkers between hexanuclear zirconium clusters. When grown on conducting substrates and under applied reductive potential, the cobaloxime linkers promote electron transport through the film as well as function as molecular HECs. The obtained turnover numbers are orders of magnitude higher than those of any other comparable cobaloxime system, and the molecular integrity of the cobaloxime catalysts is maintained for at least 18 h of electrocatalysis. Being one of the very few hydrogen evolving electrocatalytic MOFs based on a redox-active metallo-linker, this work explores uncharted terrain for greater catalyst diversity and charge transport pathways.
分子析氢催化剂（HECs）具有合成可调性，且通常表现出高活性，但它们也受到稳定性问题以及与在均相体系中使用相关的实际限制的困扰。将它们作为整体连接单元引入金属有机框架（MOFs）中可以弥补这些缺点。此外，MOFs的扩展三维结构使得每几何表面积的催化剂负载量很高。在此，我们报道了一种新型MOF，它仅由钴肟组成（钴肟是一种经过广泛研究的HEC），在六核锆簇之间充当金属连接体。当生长在导电基底上并施加还原电位时，钴肟连接体促进电子通过薄膜传输，同时起到分子析氢催化剂的作用。得到的周转数比任何其他可比的钴肟体系高出几个数量级，并且在至少18小时的电催化过程中，钴肟催化剂的分子完整性得以保持。作为基于氧化还原活性金属连接体的极少数析氢电催化MOFs之一，这项工作探索了未知领域，以实现更大的催化剂多样性和电荷传输途径。
