Recently,　polymeric　semiconductor　graphitic　carbon　nitride　(g-C3N4)　has　been　widely　used　in　fields　related　to　energy　and　material　science,　because　of　its　unique　electronic　structure　and　excellent　chemical　inertness.　For　example,　it　can　function　as　a　metal-free　catalyst　or　as　a　catalyst　support　for　organic　synthesis,　photocatalytic　water　splitting,　oxygen　reduction　reactions,　and　loading　of　Au,　Pd,　Ag,　and　Pt　nanoparticles.　In　addition,　it　can　also　serve　as　a　porous　covalent　organic　framework　for　the　absorption　of　H-2　and　CO2　gases,　or　as　a　hard　template　for　the　generation　of　metal　(oxy)nitrides.　In　this　review,　some　recent　advances　in　g-C3N4　synthesis　and　applications　are　presented.　The　prospects　for　the　development　of　g-C3N4　in　energy-　and　environment-related　fields　are　also　discussed.