Nickel-complexes with a mixed-donor ligand for photocatalytic hydrogen evolution from aqueous solutions under visible light

Increasing interest has been paid to the development of earth-abundant photocatalyst systems for production of hydrogen from water. In this work, we, for the first time, investigated the photocatalytic activities of complexes formed between β-mecaptoethylamine (L) and Ni(ii), NiL₂, and the trinuclear complex, Ni(NiL₂)₂²⁺, with a mixed S and N donor environment. Both complexes were found to be active catalysts for hydrogen evolution in aqueous solutions. In particular, a high quantum efficiency of 30.9 % at 480 nm was obtained over NiL₂ when Erythrosin yellowish was used as the photosensitizer.