Turning off hydrogen evolution via an organic dye photosensitizer in aqueous acetonitrile solution during photocatalytic CO2 reduction to CO

Achieving selective photocatalytic conversion of CO 2 in an aqueous solution is challenging owing to the generation of hydrogen as a typical by-product. Herein, a visible light-driven CO 2 conversion system was developed using Co(bpy) 2 Cl 2 as the catalyst and Acriflavine (Acr) as the photosensitizer (PS). At the optimal ratio, under visible light irradiation, the system achieved high selective CO 2 conversion to CO (∼100 %) in an aqueous acetonitrile solution, with a turnover number (TON) of 100 and a maximal turnover frequency (TOF) of 90 h −1 . Deeply studies reveal that the -NH 2 of Acr plays a vital effect on the selectivity of this photocatalytic CO 2 conversion system. The unique combination of Co(bpy) 2 Cl 2 and Acr provides an ideal platform for designing highly selective photocatalytic systems for CO 2 reduction.