A Small Organic Molecular Catalyst with Efficient Electron Accumulation for Near-unity CO₂ Photoreduction

Molecular catalysis is of great interest to CO₂ photoreduction. Various transition metal complexes have been developed as efficient molecular catalysts. However, it remains a challenge to catalyze CO₂ reduction by a small organic molecular photocatalyst, as the accumulation of multiple electrons in a small organic molecule is normally difficult for CO₂ reduction. We report herein a small organic molecular catalyst can be used for selective reduction of CO₂ to CO under visible light irradiation. The turnover number (TON) of CO formation is found to be 400±26 with near 100% selectivity in DMF/H₂ O medium. UV-Vis absorption spectroscopy, density functional theory (DFT) calculations, and spectroelectrochemical studies demonstrate that the organic molecular catalyst is capable of accumulating electrons through a 2e^- reduced product which shows good stability and is responsible for interacting with CO₂ . These findings elucidate an accessible way to develop purely organic molecular catalysts for CO₂ reduction by strengthening the electron accumulation.