Graphical AbstractVerifiedPrecise Integration of Dual-Atom Pair Sites onto a 2D Porphyrinic Metal-Organic Framework for Efficient CO2 Photoreduction
Dual-atom (DA) catalysts have exhibited great potential in regulating the catalytic performance of CO2 reduction. However, precise construction of DAs on a support remains challenging. Herein, we report the precise immobilization of M-DAs (M = Ru, Rh, Pt) onto the Zr-oxo cluster of a 2D porphyrinic metal-organic framework (2D-Ni-PCN-222) via a dimetallic complex pre-coordination strategy. The resultant M-DAs/2D-Ni-PCN-222 catalysts were applied to CO2 photoreduction using ammonia borane as the H* donor. Under visible light, the optimal catalyst, Ru-DAs/2D-Ni-PCN-222, exhibited a HCOO− production rate of 35.4 mmol g−1 h−1 with nearly 100% selectivity and a turnover frequency of 691 h−1. Kinetic isotope experiments demonstrated that the coupling rate between H* and CO2 governed the production efficiency of HCOO−. In situ experiments and density functional theory calculations disclosed that Ru-DAs with highly delocalized d electrons could accept photogenerated electrons from 2D-Ni-PCN-222 and inject them into inert CO2 molecules. Ab initio molecular dynamics simulations revealed that adaptive shortening of Ru–O coordination bonds during CO2 adsorption played a crucial role in facilitating deeper activation and the formation of an optimal η3–O,C,O adsorption mode of CO2. This work provides a precise strategy for constructing dual-atom catalysts on MOFs and elucidates the mechanism of CO2 photoreduction, offering insights for the design of efficient photocatalysts.
