Tailoring Graphitic Carbon Nitride (g-C3N4) for Multifunctional Applications: Strategies for Overcoming Challenges in Catalysis and Energy Conversion

Graphitic carbon nitride (g-C₃N₄) has been emerging as a promising material, and this review covers its synthesis, modifications, and applications. The synthesis of g-C₃N₄ comprises the use of oxygen-free, nitrogen-rich precursors and several modification approaches to address limitations, such as low surface area, rapid recombination of electron holes, and low sunlight absorption. These strategies consist in converting g-C₃N₄ into various morphologies like nanosheets, mesoporous structures, nanotubes, nanowires, nanorods, quantum dots (QDs), and thin films to create 1D, 2D, and 3D structures. The review further investigates improvement strategies, including doping, defect introduction, heterojunction formation, and coupling with carbonaceous materials, which enhance g-C₃N₄ characteristics and broaden its use. These changes enable g-C₃N₄ to be applied in a wide range of photocatalytic (H₂ production, CO₂ reduction, photoinduced bacterial disinfection, and water treatment) and noncatalytic (drug delivery, H₂O₂ production, energy storage, N₂ fixation, organic synthesis, and sensor technology) applications. Addressing key challenges, such as synthesis complexity, environmental concerns, and material stability is essential, and the review outlines the prospects for future research to overcome the g-C₃N₄ limitations and realize its full potential. This review will assist researchers to understand and explore further the synthesis, modification strategies, and applications of g-C₃N₄ in energy, environment, and healthcare.