Bio-Inspired Nife Catalysts for H2 Production

Hydrogen production through water splitting appears to be the best solution in the long run for the storage of renewable energies. Hydrogenases are organometallic enzymes containing iron and/or nickel metal centers, whose catalytic performances rival that of platinum for hydrogen evolution. Their fascinating properties make them the ideal inspiration for the design of new molecular catalysts for technological devices. However, all heterodinuclear NiFe models reported so far do not reproduce the reactivity that occurs at the active site of [NiFe] hydrogenases, a mainly Ni-centered chemistry. We will report on structural and functional NiFe mimics that display redox activity at the Ni site. We were indeed able to isolate and experimentally characterize an active NiIFeIIintermediate modelling the Ni-L state, as well as to generate a NiIIFeIIhydride species.1 A mechanistic theoretical investigation carried outby Hall et al. revealed that even if this NiIIFeIIhydride species is a relevant model of the Ni-R state,2 it requires further reductive activation before H2evolution can proceed under mild acidic conditions.Under electrocatalytic conditions, these bio-inspired catalysts display high turnover frequency for H2 evolution from mildly acidic solutions.3 More recently, we have demonstrated that such an electrocatalyst is also efficient in acidic aqueous solution.4References Brazzolotto, D.; Gennari, M.; Queyriaux, N.; Simmons, T. R.; Pecaut, J.; Demeshko, S.; Meyer, F.; Orio, M.; Artero, V.; Duboc, C. Nature Chem. 2016,8, 1054–1060. Tang, H.; Hall, M. B. J. Am. Chem. Soc. 2017,139(49), 18065-18070. Brazzolotto, D. ; Wang, L.; Tang, H.; Gennari, M.; Queyriaux, N.; Philouze, C.; Demeshko, S.; Meyer, F.; Orio, M.; Artero, V.; Hall, M.B.; Duboc, C. 2018, ACS Catal. 8 (11), 10658-10667.Md Estak, A.; Chattopadhyay, S.; Wang, L.; Brazzolotto, D.; Pramanik, D.; Aldakov, D.; Fize, J.; Morozan, A.; Gennari, M.;Duboc, C.; Dey, A.; Artero, V. 2018, Angew. Chem. Int. Ed. 57 (49), 16001-16004.