Tailoring C-defect O-doping and n-π* transition awakened porous ultra-thin carbon nitride for efficient peroxymonosulfate activation: Performances and mechanism insight

Integrating photocatalysis technology with peroxymonosulfate oxidation possesses huge potential for degrading stubborn pollutant. Herein, a porous ultra-thin carbon nitride with C-defect O-doping and advanced n-π* transition was customized by one-pot thermal-induced polymerization of molten urea assisted with paraformaldehyde. Via visible-light coupling peroxymonosulfate activation, the DCN-100 can completely photodegrade 2,4-dichlorophenol, and rate constant is 136.6 and 37.9 times that of CN and DCN-100 without peroxymonosulfate. The light-absorption of DCN-100 surpasses 550 nm, specific surface area rises from 45.03 to 98.58 m²/g, and charge behaviors are significantly improved. The effects of paraformaldehyde amount, PMS dosage, pH, 2,4-dichlorophenol concentration, different water-body, wavelength and recycling times on photodegradation performance were explored in detail. Via capture experiments, ESR, LC-MS, Fukui-function, TEXT toxicity assessment and DFT theoretical calculation, the main active substances, degradation pathway, intermediate toxicity and enhanced activity mechanism of DCN-100 were clarified. The research provides a cost-effective, high-efficiency and environmental-friendly photocatalysts to activate peroxymonosulfate for water remediating.