• • Ru-DAs/2D-Ni-PCN-222 achieves a HCOO− production rate of 35.4 mmol g−1 h−1 with nearly 100% selectivity and a turnover frequency of 691 h−1, outperforming most reported photocatalysts and demonstrating industrial relevance for formate synthesis.
• • The dimetallic complex pre-coordination strategy enables precise immobilization of M-DAs (M = Ru, Rh, Pt) onto the Zr-oxo cluster of 2D-Ni-PCN-222, overcoming the challenge of random distribution and ensuring uniform active sites.
• • Kinetic isotope experiments confirm that the coupling rate between H* and CO2 is the rate-determining step, with a kinetic isotope effect (KIE) value indicating a primary isotope effect, guiding optimization of proton sources.
• • Ab initio molecular dynamics simulations reveal adaptive shortening of Ru–O coordination bonds during CO2 adsorption, which facilitates deeper activation and formation of an η3–O,C,O adsorption mode, lowering the activation barrier and enhancing catalytic efficiency.