Trace Al/Rb regulation stabilizes Cu-Fe5C2 active sites for ambient-pressure photothermal CO2 hydrogenation to C2-C4 olefin

Photothermal hydrogenation of CO 2 offers a solar-driven route to multicarbon hydrocarbons, but controlling carbide formation and maintaining reconstructed active sites remain challenging for iron-based catalysts. Here, we develop a trace Al/Rb co-promoted CuFe 2 O 4 catalyst that enables efficient and stable photothermal CO 2 hydrogenation to light olefin under ambient pressure. The optimized catalyst achieves high C 2 -C 4 olefin selectivity of approximately 63%, suppressing CH 4 selectivity and sustaining stable photothermal-catalytic performance for 200 h. Integrated experimental characterizations and theoretical calculations reveal that the CuFe 2 O 4 precursor undergoes reaction-induced reconstruction to form Cu-Fe 5 C 2 interfacial structures. Trace Al/Rb promotion facilitates the formation and stabilization of reconstructed metal–carbide interfaces, with Al regulating the Fe-centered coordination environment and carbide stability, while Rb tunes the interfacial electronic structure and adsorption–hydrogenation balance. This cooperative regulation stabilizes carbide-based interfacial active sites and promotes CO 2 -derived C 1 intermediates toward C–C coupling and C 2 -intermediate stabilization, thereby favoring C 2 -C 4 olefin formation.