Non-metal doped graphitic carbon nitride (g-C3N4): Prospects and review on hydrogen generation via water splitting

Green and clean energy is what the world needs. A green chemical fuel which is extremely energetic, affordable, practical, and effective, is hydrogen that can simultaneously address the world's energy crisis and environmental issues. Water can be converted into hydrogen using photocatalytic materials under sunlight. Generation of suitable and sustainable photocatalytic materials might be a practical solution of above issues. Since g-C3N4 is a visible light-responsive, metal-free, and inexpensive semiconductor, it has a lot of potential as a photocatalytic material. Nevertheless, the photocatalyst g-C3N4 has reached to it's saturation point due to its inherent disadvantages. To get around these problems, g-C3N4's lattice, morphology, surface, or interface can be improved in several ways. Doping is a technique for modifying the g-C3N4 lattice. Doping with metal, nonmetal, or both can alter the structure of the g-C3N4 lattice but nonmetal is the cost-effective and efficient method for water splitting. The mechanism, type and quantity of dopant source, reaction parameters, and synthesis process involved for gC3N4 are all covered in this review. The advancements made to g-C3N4 based photocatalysts that are co-doped (binary or multiple) non-metal or metal/non-metal-doped, or both, or functional group modification as well as morphological changes were highlighted. These modifications enhanced the activity of hydrogen production by water cleavage. Additionally, the development of highly efficient doped g-C3N4 photocatalytic systems for water splitting is discussed, along with opportunities for future advancement and current challenges.