The　rare　intrinsic　active　sites　and　low　charge　transfer　capabilities　of　catalysts　cause　the　unsatisfied　selectivity　and　activity　in　photocatalytic　reduction　of　CO2.　Utilizing　single　atoms　doping　into　a　catalyst　to　overcome　these　issues　for　improving　the　catalytic　performance　may　be　a　highly　desirable　and　challenging　endeavor.　Herein,　single　atoms　Ce　doped　ZnIn2S4　(ZIS)　nanosheets　were　prepared　as　photocatalysts　for　the　reduction　of　CO2　under　visible　light,　achieving　efficient　syngas　production　of　19.8　mmol　g−1h−1,　with　an　adjustable　CO/H2　ratios　from　1:4　to　1:1.　Characterizations　results　reveal　that　Ce　single　atoms　sites　are　dispersed　on　the　surface　of　ZIS,　forming　the　abundant　S-vacancies　via　the　lattice　distortion　of　ZIS.　These　Ce　single　atoms　sites　and　S-vacancies　(Sv)　can　greatly　enhance　the　separation　and　transport　efficiency　of　photogenerated　carriers.　Density　functional　theory　calculations　and　experiment　results　exhibit　that　electrons-rich　Ce　atoms　can　selectively　absorb　and　reduce　CO2,　while　Sv　serve　as　the　active　sites　for　the　reduction　of　H2O.　This　work　offers　a　unique　horizon　for　constructing　single-atom　doped　catalysts　and　understanding　the　synergistic　catalytic　pathway　of　surface　metal　single　atoms　and　vacancies.　©　2025