Photo-Thermal Cocatalytic CO 2 Methanation over Single-Atom Alloy Clusters

Single-atom alloy (SAA) catalysts have exhibited great potential in modulating CO2 reduction performance. However, there still exist huge challenges in the precise construction of SAA on a support. Herein, the precise immobilization of M1 M2-SAA (M1 M2 = Pt1Ni, Pd1Ni, Pd1Co) onto the Zr6O8 cluster of a 2D porphyrinic metal–organic framework (2D-Ni-PCN-222) was reported through a guest-metal barrier strategy. The resultant Pt1Ni-SAA/2D-Ni-PCN-222 displayed high reaction efficiency in photothermal catalytic CO2 hydrogenation under atmospheric pressure (1 atm CO2/H2) at 150 °C, giving rise to a CH4 production rate of 1206.5 μmol·gcat–1·h–1 (287 mmol·gPt–1·h–1) with larger than 99% selectivity. Mechanism studies revealed a synergistic catalysis between the 2D-Ni-PCN-222 and Pt1Ni-SAA in CH4 production, where the Zr6O8 cluster in 2D-Ni-PCN-222 was responsible for CO2 adsorption and reduction to CO, while Pt1Ni-SAA promoted the sequential hydrogenation of CO to CH4. Ab initio molecular dynamic simulations further demonstrated the hydrogen spillover from Pt1Ni-SAA to the adjacent Zr6O8 cluster, which simultaneously enhanced the kinetics of CO2 reduction to CO at Zr6O8 cluster sites and the overall CH4 production efficiency.