Enhanced scavenger-free photocatalysis-self-Fenton degradation performance over B-doped NVs modified g-C3N4 via promoting Fe(II)/Fe(III) cycle

[Display omitted] •B-doping and nitrogen vacancy were introduced into g-C3N4 framework by simple staged calcination method.•B-doping and nitrogen vacancy accelerated the migration and transfer rate of photogenerated carriers.•The photocatalyst exhibited a high yield of H2O2 without sacrificial agents.•The degradation rate of TC in PSFs was greatly improved compared with photocatalysis and Fenton. As an advanced oxidation method, Fenton oxidation has been extensively studied in industrial wastewater treatment. However, its drawbacks such as high reagent dosage, costliness, and the generation of secondary pollutants have limited its application in urban sewage treatment. Photocatalytic in-situ hydrogen peroxide (H2O2) generation and the construction of photocatalysis-self-Fenton oxidation system (PSFs) is considered a potential approach for applying Fenton oxidation in the sewage treatment industry. In this paper, a nitrogen vacancy-modified B-doped g-C3N4 photocatalyst with high efficiency of H2O2 production without adding a scavenger was prepared based on ion-doping and defect construction. Combined with both characterization analysis and theoretical calculation, it was clarified that the modified catalyst enhanced the photo-generated charge separation and transfer. A PSFs was constructed by adding Fe2+ for the degradation of tetracycline (TC). The system produced H2O2 in-situ through photocatalytic action and promoted the Fe2+/Fe3+ cycle under the action of photo-generated electrons. The system achieved almost complete degradation of TC under the joint action of hydroxyl radicals and superoxide radicals, and maintained more than 90 % degradation efficiency after five cycles. And the efficiency of PSFs was significantly improved compared with that of single photocatalysis and photo-Fenton oxidation.