title: Cobalt and nickel diimine-dioxime complexes as molecular electrocatalysts for hydrogen evolution with low overvoltages.
abstract: 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.
authors: 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.
authors: Pierre-André
authors: PA
authors: Jacques
authors: Vincent
authors: V
authors: Artero
authors: Jacques
authors: J
authors: Pécaut
authors: Marc
authors: M
authors: Fontecave
mesh_terms: D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004560:Electricity; D004563:Electrochemistry; D004572:Electrolysis; D006859:Hydrogen / Q000032:analysis*; D007097:Imines / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010091:Oximes / Q000737:chemistry*; D011522:Protons
chemical_list: D007097:Imines; D009942:Organometallic Compounds; D010091:Oximes; D011522:Protons; D003035:Cobalt; D009532:Nickel; D006859:Hydrogen