Here　we　report　a　facile　impregnation　synthesis　of　layered　Co(OH)2　deposited　with　g-C3N4　while　the　pH　value　is　adjusted　by　using　ammonia　solution　for　photocatalytic　water　oxidation　with　UV-vis　and　visible　light　illumination.　This　surface　modification　not　only　accelerates　the　interface　transfer　rate　of　charge　carriers　but　also　reduces　the　excessive　energy　barrier　for　O-O　formation,　thus　leading　to　enhanced　reaction　kinetics　for　photocatalytic　water　oxidation.　The　optimum　oxygen　evolution　rates　(OERs)　of　the　Co(OH)2/g-C3N4　sample　reached　27.4　and　7.1　μmol　h-1　under　UV-vis　(λ　>300　nm)　and　visible　light　(λ　>420　nm)　irradiation,　which　are　5.5　and　7　times　faster　than　those　for　pristine　g-C3N4,　respectively.　These　results　underline　the　possibility　for　the　development　of　effective,　robust,　and　earth-abundant　WOCs　for　the　promotion　of　water-splitting　photocatalysis　by　sustainable　g-C3N4　polymer　photocatalysts.　(Chemical　Equation　Presented).　©　2014　American　Chemical　Society.