A cobalt(II) complex of 2,2-bipyridine, a catalyst for electro- and photo-catalytic hydrogen production in purely aqueous media

Abstract

It is apparent that coordinatively unsaturated complexes can catalyze hydrogen production via an unstable hydride intermediate. Herein we present a water soluble electrocatalyst based on a coordinatively saturated cobalt complex, [(bpy)2Co(NO3)]⋅NO31 that is formed by the reaction of 2,2-bipyridine (bpy) with Co(NO3)2·6H2O. Under photoirradiation with blue light (λmax=469nm) in air, together with [Ru(bpy)3]Cl2 and ascorbic acid in pH5.0 aqueous solution, 1 possesses photocatalytic activity for water reduction to hydrogen with an initial turnover number (TON) of 7000 per mole of catalyst at first 3h. Additionally, 1 electrocatalyze hydrogen generation from neutral water with a turnover frequency (TOF) of 403mol of hydrogen per mole of catalyst per hour (mol H2/mol catalyst/h) at an overpotential (OP) of 838mV. We hope this can afford a new method in water reduction catalysis using coordinatively saturated complexes in purely aqueous media.