Due　to　a　growing　number　of　significant　vitality　and　environmental　issues,　the　standardized　variation　of　carbon　nitride　(CN)　for　visible-light　photocatalytic　water　splitting　is　an　encouraging　scientific　topic.　By　revealing　this,　the　functionalized　monomer　2,6-dibromobenzimidazole　(BI)　was　successfully　embedded　within　the　heptazine　units　of　CN　via　a　molecular　engineering　(Co-polymerization　process)　approach,　and　the　as-synthesized　product　was　named　CN/BIx.　Thereafter,　as-synthesized　materials　were　employed　in　the　photocatalytic　production　of　hydrogen　(H-2)　via　water　splitting　and　CO2　reduction　into　CO　under　visible　light　irradiance　(lambda　=　420　nm).　Surprisingly,　the　substituent　framework　of　CN,　which　was　intimi-dated　by　the　description　of　BI　monomer,　acted　as　a　substitution　reaction　material　and　lubricated　the　elec-tronic　structure　of　CN　by　endorsing　charge　transition　dissociation,　which　in　turn　boosted　its　photocatalytic　performance　under　visible　irradiation.　The　CN/BI10.0　yields　62.8　mol　of　CO　and　18.1　mol　of　H-2　for　4　h　of　the　catalyzed　reaction　upon　photooxidation　under　light　irradiation,　emphasizing　the　max-imum　photocatalytic　performance　with　response　to　CO2-+　Correspondingly,　the　H-2　evolution　rate　(HER)　for　bulk　CN　was　estimated　as　17.6　mol/h(1),　whereas　it　was　approximated　as　203.7　mol/h(1)　for　CN/BI10.0,　which　is　10　times　higher　than　that　of　CN.　Such　a　phenomenon　also　predicts　a　substantial　encroachment　in　the　surface　area,　energy　gap,　and　chemical　properties,　along　with　promotes　the　effective　segregation　of　pho-toinduced　charge　separation　from　the　valence　band　(VB)　to　the　conduction　band　(CB)　of　CN,　thereby,　making　it　a　good　alternative　for　the　photocatalytic　water　and　CO2　reduction　reaction　process.　(c)　2022　Elsevier　B.V.　All　rights　reserved.