Integration　by　conventional　polymerization　of　different　organic　monomers　with　carbon　nitride　(CN)　is　a　scalding　topic　and　a　simple　one-pot　process.　To　change　the　electronic　structure,　chemical　composition,　and　photocatalytic　activity　of　CN,　we　report　the　deficient　quinone　ring　monomer　here.　Thermal　copolymerization　of　urea　with　2,6-diaminoantandantquinone　(DQ)　monomer　is　an　efficient　synthesis　of　a　sequence　of　modified　CN　photocatalysts.　Results　show　that　the　optical　absorption　capacity　is　improved　by　modulating　the　quinone　ring　in　the　CN　framework,　improving　its　charge　transfer　and　separation　of　photogenerated　electron　and　holes.　The　modified　CN　shows　a　notable　improvement　in　the　photocatalytic　activity　of　overall　water　splitting,　such　as　hydrogen　evolution　rate　(HER)　and　oxygen　evolution　rate　(OER).　The　co-polymerized　CN-DQ5.0　displays　a　remarkable　activity　of　520.8　μmol/h　of　H2　evolution　and　6.8　μmol/h　of　O2　evolution,　which　is　around　8　times　and　4.5　times　greater　than　CN.　The　universal　copolymerization　by　a　small,　optimized　amount　of　monomer　DQ　explores　a　remarkable　improvement　in　the　photocatalytic　activity.　Novelty　Statement:　We　manifested　the　process　of　molecular　doping　with　carbon　nitride　(CN)　semiconductor　for　utilization　of　solar　heat　radiation　into　chemical　energy　under　sunlight　perspective.　Here,　we　suggest　a　novel　nanoscopic　organic-conjugated　heterocyclic　monomer　2,6-diaminoantandantquinone　(DQ)　monomer　as　a　demonstrator　within　CN　that　boost　the　photocatalytic　properties.　An　identifiable　undulation　occurred　in　the　surface　area,　electronic　structure,　calculated　band　gap,　and　chemical　composition　analysis　of　CN　and　also　improved　its　electronic　generation　process　under　visible　light　radiance.　The　superior　photocatalyst　stimulated　a　tremendous　photocatalytic　activity　of　water　reduction　and　water　oxidation　as　enhanced　catalytic　performances　compared　of　pristine　sample,　respectively.　©　2021　John　Wiley　&　Sons　Ltd.