Abstract

Hydrogen production, through the reduction of water in electrolysers, is currently one of the most convenient ways to store energy durably, if the electrical energy is initially obtained from renewable resources. However, while electrolysis is a mature and robust technology, the most promising devices, based on proton exchange membranes, relay on the use of platinum as electrocatalyst to accelerate both hydrogen evolution and water oxidation reactions. However, this rare and expensive metal is not itself a renewable resource, so the viability of a hydrogen economy depends on the design of new efficient and robust electrocatalytic materials based on earth-abundant elements.1 A competitive alternative to platinum could be found in living micro-organisms metabolizing hydrogen thanks to hydrogenases. Catalysis in hydrogenases only requires base-metal centers (nickel and iron) and we will show how their active sites can be used as an inspiration to design new synthetic catalysts2 and we will present very recent results related to the use of these structural mimics for the development of biotechnological processes. We will then present the bio-inspired approach that we develop for a decade in the lab. We found that cobalt diimine–dioxime complexes are efficient and stable electro-catalysts for hydrogen evolution form acidic nonaqueous solutions with slightly lower overvoltages and much larger stabilities towards hydrolysis as compared to previously reported cobaloxime catalysts.3-5 We will report on different approaches for the covalent functionalization of electrode materials with such catalysts and their activity under fully aqueous conditions. Their combination with photosensitizers to design photocatalytic systems able to achieve the photochemical production of hydrogen will also be discussed.6-8

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