With　the　increasing　consumption　of　fossil　fuels,　severe　energy　shortages　and　environmental　issues　are　fast　approaching.　Therefore,　the　development　of　green　energy　resources　is　urgently　appealed.　Among　them,　the　sunlight-driven　production　of　hydrogen　fuel　with　suitable　photocatalysts　is　regarded　as　one　of　the　potential　strategies　to　meet　the　sustainable　energy　demand　in　the　future.　However,　photocatalysis　still　faces　significant　uncertainties　mainly　because　of　the　notorious　photogenerated　electron-hole　(e-h)　recombination　and　low　carriers＇　mobility.　To　achieve　high　photocatalytic　performance,　it　is　essential　to　tailor　the　spatial　charge　separation　and　fast　charge　transfervia　electronic　and　structural　manipulation　of　photocatalysts.　As　one　of　the　hot-spot　photocatalysts,　graphitic　phase　carbon　nitride　(g-C3N4)　has　received　tremendous　attention　in　the　study　of　solar-to-fuel　(STF)　conversion　and　carbon　dioxide　reduction　reactions　(CO2RR),　owing　to　intrinsic　merits,　such　as　metal-free　components,　low-cost　resources,　good　stability,　and　visible　light　response.　Recently,　considerable　progress　has　been　achieved　to　improve　the　photocatalytic　STF　efficiency　of　g-C3N4-based　materials　by　developing　strategies　of　structures　and　electric　configurations　engineering.　In　this　study,　different　modification　methods　for　g-C3N4　were　systematically　reviewed　from　the　perspective　of　defects　control　to　provide　a　new　understanding　of　its　structure-function　relationship.　Particularly,　this　study　was　composed　in　detail　from　three　aspects　to　demonstrate　the　latest　research　progress　of　g-C3N4　photocatalytic　materials.　First,　different　routes　toward　g-C3N4　with　different　shapes　were　introduced,　including　1D,　2D,　and　3D.　Second,　doping　effects　and　defect　control　on　the　separation　and　transfer　of　photogenerated　electron-hole　pairs　were　carefully　reviewed.　Finally,　heterojunctions　based　on　g-C3N4　were　summarized,　highlighting　the　Z-scheme　heterojunction.　In　addition,　some　future　directions　and　challenges　for　the　enhancement　of　the　photocatalytic　efficiency　upon　g-C3N4　were　pointed　out　according　to　our　understanding　of　photocatalytic　water　splitting.　Copyright　©2022　Chinese　Journal　of　Engineering.　All　rights　reserved.