Role of metal and non-metal dopants in modulating g-C3N4 for photocatalytic applications

Abstract

Replacement of fossil fuels with green hydrogen energy, and eradication of toxic materials from the environment need proper utilization of solar energy. Several photocatalytic materials have been exercised to provide green energy and eradicate toxic materials from the environment. Graphitic carbon nitride (g-C3N4) is a polymeric semiconductor material with remarkable stability and appropriate band structure to separate hydrogen from water and degrade toxic pollutants. However, its light absorption activity is relatively low, and the separation of excited charges is poor. The introduction of dopants is considered as an attractive technique to modulate the band structure of g-C3N4 for the absorption of more solar light and proper separation of the exited charges. In this review article, we have discussed in detail the introduction of s-block, p-block and transition metals in the structure of g-C3N4 to modulate its band structure for the improvement of solar light absorption and charge separation. Both theoretical and experimental evidences are presented in detail to discuss how the introduced dopants affect the positions of valence and conduction bands and their corresponding thermodynamic energies for the photocatalytic redox reactions. The photocatalytic activities of different doped g–C3N4–based photocatalysts are discussed broadly to acknowledge the role of several dopants in the modulation of band structure of g-C3N4. Finally, research gap and future perspectives are discussed to further investigate the mechanism of doping both theoretically as well as experimentally. We hope that this article will attract massive readers for the synthesis of doped g-C3N4 for enhanced photocatalytic efficiency.