Photothermal　Fischer-Tropsch　synthesis　represents　a　promising　strategy　for　converting　CO　into　value-added　chemicals.　Here　the　authors　report　a　Ru1Co　single　atom　alloy　catalyst　for　CO　photo-hydrogenation　to　C5+　liquid　fuels　at　ambient　pressure,　and　confirm　the　role　of　Ru　single　atoms　in　promoting　CO　activation　and　C-C　coupling　whilst　suppressing　CHx*　over-hydrogenation.　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　C5+　liquid　fuels.　Herein,　we　report　a　ruthenium-cobalt　single　atom　alloy　(Ru1Co-SAA)　catalyst　derived　from　a　layered-double-hydroxide　nanosheet　precursor.　Under　UV-Vis　irradiation　(1.80　W　cm(-2)),　Ru1Co-SAA　heats　to　200　degrees　C　and　photo-hydrogenates　CO　to　C5+　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　CHx*　intermediates,　resulting　in　a　CO　photo-hydrogenation　turnover　frequency　of　0.114　s(-1)　with　75.8%　C5+　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　C5+　liquid　fuels.　The　findings　open　new　vistas　towards　C5+　liquid　fuels　under　sunlight　at　mild　pressures.