Lewis　acids　(LAs)　or　Lewis　bases　(LBs)　have　been　recognized　as　crucial　catalytically　active　sites　for　enhancing　the　adsorption　and　conversion　of　inert　CO2.　However,　engineering　of　periodic　frustrated　Lewis　pairs　(PFLPs)　on　the　surfaces　of　semiconductor　photocatalysts　presents　significant　challenges,　and　the　synergistic　mechanism　of　PFLPs　in　CO2　photoreduction　remains　unclear.　In　this　study,　we　propose　a　strategy　that　utilizes　periodic　oxygen　vacancies　to　engineer　dual-metallic　PFLPs　on　bimetallic　oxide　semiconductor　surfaces.　We　employ　SrNb2O6-x　as　a　model　photocatalyst　to　elucidate　the　synergistic　effect　of　PFLPs　on　CO2　photoreduction.　Within　each　FLP　unit,　the　LA　(Sr2+)　captures　an　O　atom　from　CO2　while　the　LB　(Nb4+)　engages　in　an　interaction　with　the　C　atom　and　concurrently　facilitates　transfer　of　photoinduced　electrons　from　SrNb2O6-x　to　adsorbed　CO2.　Thus,　SrNb2O6-x　with　the　PFLPs-enriched　surface　exhibits　ultrahigh　CO2　adsorption　and　a　low　energy　barrier　for　CO　desorption.　Under　focused　sunlight　irradiation,　SrNb2O6-x　demonstrates　nearly　100%　selectivity　in　converting　CO2　to　CO　at　a　rate　of　25.5　mu　mol　g(-1)　h(-1).　This　study　presents　a　method　for　designing　metal　PFLPs　on　inorganic　photocatalyst　surfaces,　which　could　contribute　to　the　practical　implementation　of　CO2　photoreduction.