Emerging insights into g-C3N4–inorganic nanocomposites for eco-friendly photocatalytic degradation of organic contaminants

Abstract

The persistent presence of organic pollutants, including dyes, antibiotics, and pesticides, in water sources poses a serious threat to human and ecological health. Green and sustainable photocatalysis using semiconductor materials has emerged as an efficient and environmentally friendly approach for the mineralization of these pollutants under light irradiation, minimizing secondary pollution and energy consumption. Among various photocatalysts, graphitic carbon nitride (g-C3N4)–based inorganic nanocomposites have shown remarkable potential due to their metal-free, low-cost, and visible-light-active nature. g-C3N4 can form heterojunctions with a variety of inorganic semiconductors, including TiO2, ZnO, WO3, BiVO4, and α-Fe2O3, enhancing light absorption, charge separation, and reactive oxygen species generation. This review systematically explores the synthesis, structural properties, photocatalytic mechanisms, and pollutant degradation performance of g-C3N4–inorganic nanocomposites, with special emphasis on the sustainable degradation of synthetic dyes, pharmaceutical antibiotics, and agricultural pesticides. The influence of heterojunction type, band alignment, synthesis method, surface area, and charge carrier dynamics is critically analyzed. Finally, current challenges and future directions in the development of green and sustainable g-C3N4–inorganic nanocomposites for photocatalytic water treatment are discussed.