Dinuclear Metal Synergistic Catalysis Boosts Photochemical CO2 -to-CO Conversion.

The solar-driven CO2 reduction is a challenge in the field of "artificial photosynthesis", as most catalysts display low activity and selectivity for CO2 reduction in water-containing reaction systems as a result of competitive proton reduction. Herein, we report a dinuclear heterometallic complex, [CoZn(OH)L1 ](ClO4 )3 (CoZn), which shows extremely high photocatalytic activity and selectivity for CO2 reduction in water/acetonitrile solution. It achieves a selectivity of 98 % for CO2 -to-CO conversion, with TON and TOF values of 65000 and 1.8 s-1 , respectively, 4, 19, and 45-fold higher than the values of corresponding dinuclear homometallic [CoCo(OH)L1 ](ClO4 )3 (CoCo), [ZnZn(OH)L1 ](ClO4 )3 (ZnZn), and mononuclear [CoL2 (CH3 CN)](ClO4 )2 (Co), respectively, under the same conditions. The increased photocatalytic performance of CoZn is due to the enhanced dinuclear metal synergistic catalysis (DMSC) effect between ZnII and CoII , which dramatically lowers the activation barriers of both transition states of CO2 reduction.