Tuning　surface　termination　can　improve　the　carrier　dynamics　and　photoredox　performance　of　photocatalysts　by　modifying　the　surface　physicochemical　properties.　Herein,　we　prepared　a　Si　photocatalyst　by　magnesium-thermal　reduction　and　then　treated　it　with　trifluoroacetic　acid　(TFA).　The　as-obtained　TFA-terminated　Si　photocatalyst　(TFA-Si)　improves　double-layer　capacitance　and　electrochemical/Brunauer-Emmet-Teller　surface　area,　rendering　more　active　sites.　Moreover,　the　TFA　modification　causes　an　increase　in　wettability,　charge　carrier　density,　and　photocurrent　and　a　reduction　in　electrochemical　impedance　and　overpotential,　which　enhances　the　adsorption/reduction　of　water　molecules　and　the　photoexcited-carrier　dynamics　for　photocatalysis.　TFA-Si　shows　high　photocatalytic　H2　evolution　activity　(1827　μmol·g-1·h-1)　in　pure　water　under　visible　light.　The　AQY　of　TFA-Si　reached　6.1%　at　400　nm.　Interestingly,　TFA　molecules　promote　the　oxidation　capacity　of　Si　photocatalysts　for　water　oxidation　through　a　hole　transfer　pathway,　boosting　its　activity　and　stability.　This　work　broadens　the　applications　of　Si-based　materials　for　use　in　photocatalysis.　©　2023　American　Chemical　Society.