The　search　for　earth-abundant　semiconductors　and　co-catalysts　for　water　oxidation　is　an　important　step　towards　conversion　of　solar　energy　into　fuel　chemicals　in　a　sustainable　manner.　Here,　we　report　the　integration　of　Co3O4　nanoparticles　within　graphitic　carbon　nitride　to　construct　a　nanohybrid　photocatalyst　made　of　abundant　elements　for　the　photocatalytic　generation　of　oxygen　from　water,　achieving　an　apparent　quantum　efficiency　of　1.1%　at　420　nm　for　water　splitting　to　oxygen.　The　present　system　shows　great　promise　in　polymer　photocatalysis　for　applications　in　future　energy　cycles　based　on　sustainable　materials.