Recent insights into g-C3N4 based composites for methylene blue photocatalytic degradation

• It is the first systematic review on Photocatalytic Degradation of Methylene Blue using composites based on g-C3N4. • Various chemical/physical technologies can be used for Photocatalytic Degradation of Methylene Blue using composites based on g-C3N4. • Removal efficiencies and operating conditions of studied technologies are reviewed. Industrial dyes, particularly toxic organic compounds like Methylene Blue (MB), pose significant threats to aquatic ecosystems and human health. Among various water treatment strategies, photocatalysis has emerged as a highly efficient and environmentally friendly technique for degrading such pollutants. This process leverages light-responsive materials to initiate redox reactions that break down contaminants. Graphitic carbon nitride (g-C 3 N 4 ), a metal-free polymeric semiconductor, has garnered considerable attention due to its visible light absorption, chemical stability, and tunable electronic properties. Nevertheless, pristine g-C 3 N 4 suffers from inadequate light absorption capability, rapid charge recombination and low specific surface area, which restricts its photocatalytic efficiency. To overcome limitations, researchers have extensively explored the development of g-C 3 N 4 based composites. These composites integrate g-C 3 N 4 with other materials, such as metal, metal oxides, carbon-based materials, or other semiconductors, to create heterostructures with enhanced properties. This review summarizes the latest photocatalytic applications of g-C 3 N 4 based nanocomposites toward degradation of MB. The main objective of this study was to evaluate the mechanisms involved and investigate the role of operational parameters. This review ends with kinetics perspective of photocatalytic degradation of MB via g-C 3 N 4 based catalysts and several insights on the future avenues in investigating practical applications of photocatalytic degradation of organic pollutants via g-C 3 N 4 based catalysts.