Development of a g-C3N4-based photocatalysis-self-Fenton system for efficient degradation and mineralization of organic pollutants

• A photocatalysis-self-Fenton system based on g-C 3 N 4 is successfully constructed. • P heteroatoms and cyano groups are introduced into g-C 3 N 4 to improve its availability for O 2 and H + , boosting its H 2 O 2 production. • Inhibiting H 2 O 2 decomposition into ·OH on the g-C 3 N 4 surface ensures excellent durability of the photocatalysis-self-Fenton system; • The ·OH steady-state concentration in the photocatalysis-self-Fenton system is 42.2 times higher than in the photocatalytic system. Photocatalytic water treatment holds great promise for addressing global challenges associated with energy shortage and water scarcity. However, despite decades of research, its practical implementation remains constrained by the limited efficiency in generating and utilizing hydroxyl radicals (·OH). To this end, this study develops a photocatalysis-self-Fenton system based on graphitic carbon nitride (g-C 3 N 4 ). By introducing P heteroatoms into the g-C 3 N 4 matrix, we enhance O 2 adsorption, while the incorporation of cyano groups improves H + adsorption (both of which favor H 2 O 2 generation) and prevents the generated H 2 O 2 from decomposing into ·OH on the catalyst surface. This system boosts the steady-state concentration of · OH by approximately 42 times compared to photocatalytic system, while the homogeneous generation of ·OH further enhances its utilization. As a result, it enables the complete degradation of 2,4-Dichlorophenol in only 20 min under visible light, with a mineralization rate of 71.21%. Additionally, this system demonstrates broad applicability, achieving removal efficiencies exceeding 90% for various typical organic pollutants (4-chlorophenol, bisphenol A, norfloxacin, ciprofloxacin, and sulfadiazine). Furthermore, its durability across multiple cycles underscores its potential for practical water treatment applications.