Sluggish　hole　transfer　and　the　resulting　pronounced　charge　recombination　hinder　the　efficiency　of　photocatalytic　overall　water　splitting.　Herein,　we　present　Si　quantum　dots　(SiQDs)　as　hole　transporter　to　construct　SiQDs/Cu-doped　ZnIn2S4　heterojunction　photocatalysts　(Cu0.48SZ)　for　overall　water　splitting.　Under　visible　light　illumination,　Cu0.48SZ　exhibits　highly　stable　overall　water-splitting　activity　of　210　μmol　g−1　h−1　H2　and　97　μmol　g−1　h−1　O2　with　an　apparent　quantum　yield　(AQY)　of　2.57　%　at　420　nm.　Results　demonstrate　that　the　synergy　of　SiQDs　and　Cu　doping　enhances　carrier-separation　efficiency　and　reduce　surface　kinetic　barriers,　leading　to　high　photocatalytic　performance.　The　presence　of　SiQDs　effectively　accelerates　the　transfer　of　photoexcited　holes　and　avoids　the　self-oxidation　of　ZnIn2S4,　favoring　water　oxidation.　The　Cu　doping　increases　the　electron　density　around　the　S　atoms　of　ZnIn2S4　and　thus　promotes　water　reduction.　This　work　extends　the　application　of　SiQDS　as　efficient　hole　transporter　for　photocatalytic　overall　water　splitting.　©　2024　Elsevier　B.V.