Publication 838

Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong, P. R. China
nstitute of Molecular Functional Materials and Department of Chemistry, City University of Hong Kong, Kowloon Tong, Hong Kong, P. R. China
Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Electrochimie Moléculaire, Unité Mixte de Recherche Université-CNRS no. 7591, Paris Cedex 13, France

The invention of efficient systems for the photocatalytic reduction of CO₂ comprising earth-abundant metal catalysts is a promising approach for the production of solar fuels. One bottleneck is to design highly selective and robust molecular complexes that are able to transform the CO₂ gas. The Cu^II quaterpyridine complex [Cu(qpy)]²⁺ (1) is found to be a highly efficient and selective catalyst for visible-light driven CO₂ reduction in CH₃CN using [Ru(bpy)₃]²⁺ (bpy: bipyridine) as photosensitizer and BIH/TEOA (1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole/triethanolamine) as sacrificial reductant. The photocatalytic reaction is greatly enhanced by the presence of H₂O (1–4 % v/v), and a turnover number of >12 400 for CO production can be achieved with 97 % selectivity, which is among the highest of molecular 3d CO₂ reduction catalysts. Results from Hg poisoning and dynamic light scattering experiments suggest that this photocatalyst is homogenous. To the best of our knowledge, 1 is the first example of molecular Cu-based catalyst for the photoreduction of CO₂.