Researchers in the field of photocatalysis are interested in finding a solution to the problem of charge transfer and recombination in photodegradation mechanisms. The ideal photoactive catalyst would be inexpensive, environmentally friendly, easily manufactured, and highly efficient. Graphitic carbon nitride (g-C3N4) and metal oxide (MOx) based nanocomposites (g-CN/MOx) are among the photocatalysts that provide the best results in terms of charge transfer capacity, redox capabilities, and charge recombination inhibition. This article provides a comprehensive overview of the latest research on antibiotic removal from wastewater using photocatalysts based on g-C3N4 and metal oxides nanocomposites. Amoxicillin (AMX), Azithromycin (AZM), Cefixime (CFM), Ciprofloxacin (CIP), and Tetracycline (TC) are some of the common antibiotics that are the focus of this review article's examination of the photocatalytic behavior of various g-C3N4/metal oxide-based photocatalysts. A research gap demonstrates that many studies are required to use these nanocomposites for photodegradation of antibiotics. By providing a better grasp of the photocatalysis process, this review encourages scientists and researchers to develop an accurate and appropriate photocatalyst to reduce environmental risks. The main findings of this review article suggest that the cost-effective g-C3N4/MOx-based nanocomposites exhibit excellent photodegradation properties, high charge transfer, broadening light response, and charge separation. They promote enhanced charge transportation, superior electron conductivity, high redox capability, and suppressing charge recombination rate. The photodegradation mechanism involves various reactive oxygen species (ROSs), including superoxide radicals, hydroxyl radicals, and holes which promotes the photocatalysis process. The exact transportation mechanism of electrons and holes is unclear, but a rapid charge-carrier transit can significantly increase and speed up the photooxidation process.
Universal access to clean water has been a global ambition over the years. Photocatalytic water disinfection through advanced oxidation processes has been regarded as one of the promising methods for breaking down microbials. The forefront of this research focuses on the application of metal-free photocatalysts for disinfection to prevent secondary pollution. Graphitic carbon nitride (g-C3 N4 ) has achieved instant attention as a metal-free and visible-light-responsive photocatalyst for various energy and environmental applications. However, the photocatalytic efficiency of g-C3 N4 is still affected by its rapid charge recombination and sluggish electron-transfer kinetics. In this contribution, two-dimensionally protonated g-C3 N4 was employed as metal-free photocatalyst for water treatment and demonstrated 100 % of Escherichia coli within 4 h under irradiation with a 23 W light bulb. The introduction of protonation can modulate the surface charge of g-C3 N4 ; this enhances its conductivity and provides a "highway" for the delocalization of electrons. This work highlights the potential of conjugated polymers in antibacterial application.