Efficient Visible-Light-Driven Carbon Dioxide Reduction using a Bioinspired Nickel Molecular Catalyst.

Inspired by natural enzymes, this study presents a nickel-based molecular catalyst, [Ni(NS)]Cl (NiNS, NS=2,11-dithia3,3pyridinophane), for the photochemical catalytic reduction of CO under visible light. The catalyst was synthesized and characterized using various techniques, including liquid chromatography-high resolution mass spectrometry (LC-HRMS), UV-Visible spectroscopy, and X-ray crystallography. The crystallographic analysis revealed a slightly distorted octahedral coordination geometry with a mononuclear Ni cation, two nitrogen atoms and two sulfur atoms. Photocatalytic CO reduction experiments were performed in homogeneous conditions using the catalyst in combination with [Ru(bpy)]Cl (bpy=2,2'-bipyridine) as a photosensitizer and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH) as a sacrificial electron donor. The catalyst achieved a high selectivity of 89 % towards CO and a remarkable turnover number (TON) of 7991 during 8 h of visible light irradiation under CO in the presence of phenol as a co-substrate. The turnover frequency (TOF) in the initial 6 h was 1079 h, with an apparent quantum yield (AQY) of 1.08 %. Controlled experiments confirmed the dependency on the catalyst, light, and sacrificial electron donor for the CO reduction process. These findings demonstrate this bioinspired nickel molecular catalyst could be effective for fast and efficient photochemical catalytic reduction of CO to CO.