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• Fe-POM NP/porous and ultrathin g-C 3 N 4 nanosheet with rich N defect was fabricated. • Various emerging pollutants were almost completely removed by 45Fe- POM/CNNS-N vac. • Impact of N vacancies on ROS degradation mechanism was investigated. • Degradation pathways and products toxicity were given via theoritical calculation. Surface defect engineering has been suggested as an effective strategy to enhance photo-Fenton degradation performance. However, the underlying impact mechanism remains unknown. This study precisely constructed an efficient photo-Fenton catalyst through self-assembly of Fe-polyoxometalates nanoparticles on porous and ultrathin g-C 3 N 4 nanosheets with nitrogen vacancies (Fe-POM/CNNS-N vac). These nitrogen vacancies promoted photo-Fenton reaction rate constant for tetracycline hydrochloride (TCH) from 0.0950 to 0.1520 min−1 under visible light irradiation. Scavenging experiments and characterization results indicated that nitrogen vacancies could accelerate Fe(III)/Fe(II) conversion for OH and 1O 2 generation, and directly regulate electronic structure for O 2 − generation. The possible degradation pathways of TCH were interpreted using experimental results and frontier electron density calculations. The results indicated that holes (h+) were responsible for ring-opening and 1O 2 /OH/O 2 − contributed to demethylation, deamination, and further mineralization. This study provides novel insight for the design of highly efficient catalysts with nitrogen vacancies for the removal of emerging pollutants. [ABSTRACT FROM AUTHOR]

The design of suitable catalyst is the bottleneck in the photo-assisted Fenton-like reaction system. Here we constructed a S-scheme heterojunction consisted of CuO and Cu doped ZnO using Cu-ZIF-8 as precursor. The as-prepared composite catalyst possesses outstanding catalytic activation performance and broad-spectrum degradation capacity. To clearly fit and describe the overall reaction, a pseudo-third-order kinetic model was developed based on the second-order peroxymonosulfate (PMS) consumption and first-order methylene blue removal. The catalyst/visible light/ PMS composite reaction system provides remarkable mineralization and anti-interference ability, and is environmental friendliness. The interaction of Cu/Zn bimetallic sites realized the effective utilization of PMS, accelerated the PMS activation and promoted the formation of the highly oxidative SO 5 •−. Overall, this work provides new systematic insights on PMS activation by Cu/Zn bimetallic oxide S-scheme heterojunction and is of significance for sewage purification. [Display omitted] • A S-scheme heterojunction was constructed by using Cu-ZIF-8 as precursor. • The as-prepared CuZnO-3 exhibited superior catalytic activation capability. • A pseudo-third-order kinetic model was developed involving the reacted MB and PMS. • The CuZnO-3/vis/PMS reaction system was evaluated to be environmentally friendly. • The catalytic activation mechanism of Cu/Zn bimetallic sites was proposed. [ABSTRACT FROM AUTHOR]