Robust Binding between Carbon Nitride Nanosheets and a Binuclear Ruthenium(II) Complex Enabling Durable, Selective CO2 Reduction under Visible Light in Aqueous Solution

Carbon nitride nanosheets (NS‐C3N4) were found to undergo robust binding with a binuclear ruthenium(II) complex (RuRu′) even in basic aqueous solution. A hybrid material consisting of NS‐C3N4 (further modified with nanoparticulate Ag) and RuRu′ promoted the photocatalytic reduction of CO2 to formate in aqueous media, in conjunction with high selectivity (approximately 98 %) and a good turnover number (>2000 with respect to the loaded Ru complex). These represent the highest values yet reported for a powder‐based photocatalytic system during CO2 reduction under visible light in an aqueous environment. We also assessed the desorption of RuRu′ from the Ag/C3N4 surface, a factor that can contribute to a loss of activity. It was determined that desorption is not induced by salt additives, pH changes, or photoirradiation, which partly explains the high photocatalytic performance of this material. Fixed to fix: Carbon nitride nanosheets bind strongly with a binuclear ruthenium(II) complex even in basic aqueous solution, enabling durable, selective CO2 reduction into formate under visible light.