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

Abstract Carbon nitride nanosheets (NS‐C 3 N 4 ) were found to undergo robust binding with a binuclear ruthenium(II) complex ( RuRu′ ) even in basic aqueous solution. A hybrid material consisting of NS‐C 3 N 4 (further modified with nanoparticulate Ag) and RuRu ′ promoted the photocatalytic reduction of CO 2 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 CO 2 reduction under visible light in an aqueous environment. We also assessed the desorption of RuRu ′ from the Ag/C 3 N 4 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.