Photodegradation of microplastics using graphitic carbon nitride (g-C3N4) based nanocomposite materials: A recent development on environmental remediation and bibliometric study

Microplastic (MP) pollution has become a major environmental issue because of its continuous worldwide distribution of harmful effects on human health as well as aquatic ecosystem. Graphitic carbon nitride (g-C 3 N 4 ), a metal-free polymer-based semiconductor, has gained attention as a promising photocatalyst for microplastic degradation because of its enhanced visible-light activity, high chemical durability and adjustable electronic structure. This review along with bibliometric analysis highlights the current progress in the synthesis, structural modifications and heterojunction construction of g-C 3 N 4 based materials to enhance photocatalytic activity. The mechanism of microplastic degradation, including the generation of hydroxyl radicals, superoxide radicals and photogenerated holes and electrons are discussed along with factors influencing performances such as light intensity, source of irradiation, pH, temperature, type and size of microplastic. The current challenges, including large-scale application, and treatment of mixed microplastics under real environmental conditions are studied. The future directions for the development of multifunctional and practical g-C 3 N 4 based photocatalysts in sustainable microplastic remediation are proposed.