A molecular cobalt catalyst supported by an amine-bis(phenolate) ligand for both electrolytic and photolytic water reduction

Abstract

A new molecular catalyst based on cobalt complex [L₂Co₂Cl₂] 1 is prepared by the reaction of an amine-bis(phenolate) ligand (H₂L) with CoCl₂·6H₂O for both electrolytic and photolytic water reduction. 1 can electrocatalyze hydrogen evolution from water with a turnover frequency (TOF) of 789.6 moles of hydrogen per mole of catalyst per hour at an overpotential of 837.6 mV (pH 7.0). 1 in a pH 6.0 aqueous solution under air, together with [Ru(bpy)₃]Cl₂ and ascorbic acid, in the presence of blue light (λ_max = 469 nm) also produces hydrogen with a turnover number (TON) = 912 mol of H₂ (mol of cat)⁻¹.