Visible-light-driven methane formation from CO2 in hydrous solution with a dinuclear nickel catalyst

Abstract The photocatalytic reduction of CO2 to CH4 in a hydrous solution was successfully achieved by a homogeneous molecular catalytic system involving two dinuclear nickel complex catalysts (i.e., [(dmbpy)2Ni2Cl4(H2O)2] (1) (dmbpy = 4,4′-dimethyl-2,2′-bipyridine) and [(bpy)2Ni2Cl4(H2O)2] (2) (bpy = 2,2′-bipyridine)), in the presence of [Ru(bpy)32+] or organic dye such as Eosin Y as a photosensitizer. Control and cyclic voltammetry experiments (CV) revealed that H2O could provide the H+ required for the conversion of CO2 into CH4 and ruled out CO as an intermediate in this reaction.