A　prepared　p-type　PdO/n-type　TiO2　junction　was　prepared　as　the　catalyst　for　photocatalytic　hydrogen　evolution　from　formic　acid　(FA).　It　was　found　that　PdO/TiO2　exhibited　1298-fold　higher　activity　than　TiO2　under　ultraviolet　and　visible　light　irradiation　at　room　temperature.　Multiple　characterization　techniques　were　utilized　to　demonstrate　that　doping　PdO　into　TiO2　can　regulate　the　Fermi　level　of　the　sample　and　the　adsorption　behavior　of　FA,　resulting　in　different　electron　transfer　behavior　between　FA　and　PdO/TiO2　compared　to　that　between　FA　and　TiO2.　Oxygen　vacancies　acted　as　electron　donors　to　deliver　photogenerated　electrons　from　TiO2　to　the　adsorbed　bidentate　FA,　which　increased　the　electron　density　on　the　O　atom　of　FA　and　led　to　the　formation　of　activated　monodentate　FA.　This　activated　FA　was　more　easily　oxidized　by　the　holes　in　PdO　generated　by　visible　light,　leading　to　the　production　of　H2　and　CO2.　The　mode　of　adsorption　associated　with　the　Pd2+　site　is　the　key　factor　in　driving　this　reaction　and　leading　to　the　reversible　electron　transfer　phenomenon.　This　study　provides　a　new　promising　route　for　the　design　of　photocatalysts　for　self-decomposition　reactions.　©　2024　Elsevier　Ltd