4. Graphitic Carbon Nitride (g-C₃N₄)-Based Photocatalysts for Environmental Applications

The alarmingly rising environmental pollution adversely affects the sustainable growth of modern civilization. Scientists have persistently been putting tremendous efforts over the decades to develop environment benevolent technologies to overcome this major challenge. Photocatalysis is one such technology which needs renewable solar energy and abundantly available water resources as driving forces for pollutants’ degradation. In addition, the selection of an appropriate semiconductor is highly essential to degrade toxic organic compounds, hazardous heavy metals and noxious gases into harmless products efficiently. Among various semiconductor photocatalysts, g‑C₃N₄ (GCN) is considered a robust photocatalyst because of several fascinating properties like metal-free chemical nature, visible-light-responsive activity with moderate band gap of 2.7 eV, tunable electronic structure, facile synthesis, low cost, high thermal and chemical stability. However, low surface area (∼10 m² g⁻¹), high rate of charge carriers recombination, incomplete solar spectrum absorbance and inadequate valence band position (1.4 eV vs NHE) are some of the limitations due to which expected photocatalytic performance of GCN is yet to be achieved. Therefore, modification strategies such as exfoliating bulk GCN into nanosheets, incorporating foreign elements into its crystal structure and heterostructure formation have been employed to overcome these limitations to achieve high photocatalytic efficiency. In this chapter discusses the basic principle of photocatalytic pollutant degradation over a semiconductor surface. Recent developments in modification strategies to enhance the photoactivity of GCN have been summarised systematically. Photocatalytic applications of GCN-based photocatalysts with respect to environmental remediation are presented in this chapter. The challenges and future perspectives in designing GCN-based photocatalysts for efficient performance towards environmental applications are addressed along with the conclusion.