Graphitic carbon nitride-based photocatalysts for the degradation of contaminants of emerging concern: recent advances and future perspectives

Abstract

Contaminants of emerging concern (CECs), such as pharmaceuticals, endocrine disrupting compounds, and personal care products are frequently reported in aquatic environments, which pose serious risks to ecosystems and human health for their potential persistence and resistance to traditional wastewater treatment. Photocatalysis has emerged as one of the most promising sustainable and efficient strategies for degradation of these contaminants. The graphitic carbon nitride (g-C3N4), as a photocatalyst has gained wide interest owing to its metal-free nature, appropriate bandgap (∼2.7 eV) and excellent chemical stability. However, its practical utilization is restricted by low quantum efficiency and fast charge recombination. This review comprehensively discusses the occurrence and environmental impact of CECs, fundamentals of g-C3N4 photocatalysis, synthesis approaches, characterization techniques, photocatalytic mechanisms, and recent modification strategies developed to overcome the intrinsic limitations of pristine g-C3N4. Particular emphasis is placed on the relationship between structural engineering and photocatalytic performance in the degradation of various CECs. The review also discusses the main challenges such as catalyst deactivation, transformation product toxicity, and mass production restrictions. Finally, some emerging directions like AI-guided materials design, green synthesis pathways and pilot-scale practices are discussed that could be explored to close the gap between lab research and real-world applications.