Photothermal Fischer-Tropsch synthesis represents a promising strategy for converting carbon monoxide into value-added chemicals. High pressures (2-5 MPa) are typically required for efficient C-C coupling reactions and the production of C liquid fuels. Herein, we report a ruthenium-cobalt single atom alloy (Ru Co-SAA) catalyst derived from a layered-double-hydroxide nanosheet precursor. Under UV-Vis irradiation (1.80 W cm ), Ru Co-SAA heats to 200 °C and photo-hydrogenates CO to C liquid fuels at ambient pressures (0.1-0.5 MPa). Single atom Ru sites dramatically enhance the dissociative adsorption of CO, whilst promoting C-C coupling reactions and suppressing over-hydrogenation of CH * intermediates, resulting in a CO photo-hydrogenation turnover frequency of 0.114 s with 75.8% C selectivity. Owing to the local Ru-Co coordination, highly unsaturated intermediates are generated during C-C coupling reactions, thereby improving the probability of carbon chain growth into C liquid fuels. The findings open new vistas towards C liquid fuels under sunlight at mild pressures.