(A) Schematic synthetic route for MCBt supramolecular assemblies. Adapted with permission from [81]. Copyright 2018, Elsevier. (B) Schematic representation of chemical reaction for the synthesis of GCNNF. Adapted with permission from [86]. Copyright 2014, American Chemical Society. (C) Formative process of oxygen-doped C₃N₄ nanotubes. Adapted with permission from [42]. Copyright 2021, Elsevier. (D) Schematic representation of the synthesized process of MTCN. Adapted with permission from [90]. Copyright 2018, Elsevier. (E) The formation of C₃N₄ nanostructures (CNWs and CNFs). Adapted with permission from [93]. Copyright 2016, Elsevier. (F) Synthetic route towards C-rich C₃N₄ with a carbon layer gradient. Adapted with permission from [97]. Copyright 2018, Royal Society of Chemistry.