Self-adaptive dual-metal-site pairs in metal-organic frameworks for selective CO2 photoreduction to CH4

Solar-light-driven reduction of CO 2 -to-CH 4 is a complex process involving multiple elementary reactions and various by-products. Achieving high CH 4 activity and selectivity therefore remain a significant challenge. Here we show a bioinspired photocatalyst with flexible dual-metal-site pairs (DMSPs), which exhibit dynamic self-adaptive behaviour to fit mutative C1 intermediates, achieving CO 2 -to-CH 4 photoreduction. The Cu and Ni DMSPs in their respective single-site forms under flexible microenvironment are incorporated into a metal-organic framework (MOF) to afford MOF-808-CuNi. This dramatically boosts CH 4 selectivity up to 99.4% (electron basis) and 97.5% (product basis), and results in a high production rate of 158.7 μmol g −1 h −1 with a sacrificial reagent. Density functional theory calculations reveal that the flexible self-adaptive DMSPs can stabilize various C1 intermediates in multistep elementary reactions, leading to highly selective CO 2 -to-CH 4 process. This work demonstrates that efficient and selective heterogeneous catalytic processes can be achieved by stabilizing reaction intermediates via the self-adaptive DMSP mechanism. CH 4 selectivity in CO 2 photoreduction is a kinetic challenge as a result of the complex pathway involving many intermediates. Here, the authors present dual-metal-site pairs embedded in a metal-organic framework structure with flexible adaptive active sites leading to high CH 4 activity and selectivity.