Visible‐Light‐Driven CO₂ Reduction with Carbon Nitride: Enhancing the Activity of Ruthenium Catalysts

A heterogeneous photocatalyst system that consists of a ruthenium complex and carbon nitride (C 3 N 4 ), which act as the catalytic and light‐harvesting units, respectively, was developed for the reduction of CO 2 into formic acid. Promoting the injection of electrons from C 3 N 4 into the ruthenium unit as well as strengthening the electronic interactions between the two units enhanced its activity. The use of a suitable solvent further improved the performance, resulting in a turnover number of greater than 1000 and an apparent quantum yield of 5.7 % at 400 nm. These are the best values that have been reported for heterogeneous photocatalysts for CO 2 reduction under visible‐light irradiation to date.