Graphitic　carbon　nitride　(g-C3N4)　is　a　non-metallic　semiconductor,　that　has　received　enormous　interest　in　the　research　area　of　energy　conversion　and　storage　due　to　its　several　exceptional　characteristics　such　as　moderate　bandgap,　high　thermal　and　chemical　stability,　cost-effectiveness,　and　perfect　conduction　and　valence　band　position.　Nevertheless,　the　catalytic　performance　of　g-C3N4　is　considerably　constrained　owing　to　its　low　solar　light　absorption,　small　surface　area,　and　quick　photoinduced　charge　recombination.　Enormous　studies　have　been　dedicated　to　the　optimization　of　photoresponsive　efficiency　through　structure　engineering,　resulting　in　a　variety　of　techniques　for　achieving　productive　photoresponsive　applications　based　on　a　perspective　of　the　photoexcitation　mechanisms　and　structural　characteristics　of　the　exciting　polymeric　framework.　This　review　examines　the　impact　of　vacancy　defects　within　g-C3N4　such　as　carbon　vacancies　(CVs),　nitrogen　vacancies　(NVs),　amino　vacancies,　a　combination　of　cyano　groups　with　narrow　optical　gap　materials,　bandgap　engineering,　upconversion　materials,　plasmonic　materials,　and　photosensitizers　have　been　briefly　described.　In　addition,　numerous　analyzing　techniques　such　as　microscopic,　elemental,　and　computational　characterizations　have　been　summed　up　and　investigated.　Significantly,　this　review　also　describes　the　physicochemical　features　of　g-C3N4　and　highlights　the　synthetic　procedures　for　g-C3N4　morphology　including　thermal　oxidation　etching,　chemical　exfoliation,　ultrasonication-assisted　liquid　phase　exfoliation,　chemical　vapor　deposition,　etc.　Moreover,　the　universal　optimization　methodologies　for　the　synthesis　of　advanced　photoresponsive　materials,　the　optimistic　light　between　structural　variables,　and　photoexcitation　mechanisms　in　g–C3N4–based　materials　have　been　explored.　Furthermore,　the　rational　development　and　sustainable　fabrications　of　g–C3N4–based　materials　for　a　wide　range　of　applications　in　energy　conversion　and　storage,　such　as　photocatalytic　H2　evolution,　photocatalytic　O2　evolution,　photocatalytic　overall　water　splitting,　photoreduction　of　CO2　source,　electrocatalytic　H2　evolution,　O2　evolution,　O2　reduction,　alkali-metal　ion　batteries,　lithium-metal　batteries,　lithium-sulfur　batteries,　metal-air　batteries,　and　supercapacitors　have　been　discussed　in　detail.　In　the　end,　the　future　challenges　and　opportunities　with　a　brief　discussion　on　the　developments　of　novel　g–C3N4–based　materials　have　been　concluded.　©　2023　Elsevier　Ltd