Bismuth　vanadate　(BiVO4)　is　one　of　the　most　promising　metal　oxide　semiconductors　for　photoelectrochemical　(PEC)　water　oxidation.　Much　efforts　have　been　dedicated　on　accelerating　the　sluggish　surface　water　oxidation　kinetics.　In　this　study,　plasma　enhanced　atomic　layer　deposition　and　subsequent　removal　of　Al2O3　ultrathin　overlayers　on　bismuth　vanadate　were　implemented　to　achieve　the　successful　passivation　of　surface　states　and　significant　enhancement　of　PEC　performance.　Al2O3　ultrathin　overlayers　were　first　coated　on　BiVO4　surface　via　plasma　enhanced　atomic　layer　deposition　with　various　deposition　cycles,　which　resulted　in　the　decrease　of　PEC　water　oxidation　activity　due　to　the　poor　conductivity.　The　subsequent　removal　of　surface　amorphous　Al2O3　passivated　the　surface　states　of　the　photoanodes　and　significantly　enhanced　the　photocurrent　densities.　The　passivated　BiVO4　exhibited　a　photocurrent　density　of　1.34　mA·cm−2　at　1.23　V　vs.　RHE,　which　is　73%　higher　than　that　of　unmodified　BiVO4.　This　work　provides　a　novel　strategy　and　deep　insights　on　surface　modification　of　semiconductor　for　photoelectrochemical　energy　conversion.　©　2021　Elsevier　B.V.