Laboratoire de Chimie et Biologie des Métaux, Université Joseph Fourier, Grenoble, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5249, CEA, DSV/iRTSV, 17 rue des Martyrs, F-38054 Grenoble cedex 9, France.
Proc Natl Acad Sci U S A. 2009 Dec 8;106(49):20627-32. doi: 10.1073/pnas.0907775106. Epub 2009 Nov 30.
Hydrogen production through the reduction of water appears to be a convenient solution for the long-run storage of renewable energies. However, economically viable hydrogen production requests platinum-free catalysts, because this expensive and scarce (only 37 ppb in the Earth's crust) metal is not a sustainable resource [Gordon RB, Bertram M, Graedel TE (2006) Proc Natl Acad Sci USA 103:1209-1214]. Here, we report on a new family of cobalt and nickel diimine-dioxime complexes as efficient and stable electrocatalysts for hydrogen evolution from acidic nonaqueous solutions with slightly lower overvoltages and much larger stabilities towards hydrolysis as compared to previously reported cobaloxime catalysts. A mechanistic study allowed us to determine that hydrogen evolution likely proceeds through a bimetallic homolytic pathway. The presence of a proton-exchanging site in the ligand, furthermore, provides an exquisite mechanism for tuning the electrocatalytic potential for hydrogen evolution of these compounds in response to variations of the acidity of the solution, a feature only reported for native hydrogenase enzymes so far.
通过还原水来生产氢气，似乎是一种将可再生能源进行长期储存的便捷解决方案。然而，经济可行的氢气生产需要无铂催化剂，因为这种昂贵且稀缺（地壳中仅 37 个 ppb）的金属不是可持续资源[Gordon RB, Bertram M, Graedel TE（2006）Proc Natl Acad Sci USA 103:1209-1214]。在这里，我们报告了一类新型钴和镍二亚胺-二恶唑啉配合物，它们作为高效且稳定的电催化剂，可在酸性非水溶剂中催化氢的析出，与之前报道的钴卟啉催化剂相比，其过电势略低，水解稳定性更高。一项机理研究表明，氢的析出可能通过双金属均裂途径进行。此外，配体中存在质子交换位点，为这些化合物的电催化析氢性能提供了一种精细的调节机制，这种特性迄今为止仅在天然氢化酶中报道过。
