Z-scheme heterojunction Fe-g-C3N4/MoO3-x photocatalyst can effectively activate peroxymonosulfate to degrade humic acid under visible light irradiation

The photo-Fenton-like process is commonly used to degrade organic pollutants in environmental pollution. In this study, a Z-scheme heterojunction Fe-g-C3N4/MoO3-x photocatalyst was prepared by a calcination-hydrothermal two-step method. The results of photo-Fenton-like degradation of humic acid showed that the FCNM-8/PMS/Vis system achieved a degradation activity of 97.42 % for HA (10 mg/L) within 120 min, which was due to the successful construction of a heterojunction between Fe-g-C3N4 and MoO3-x. The efficient charge separation efficiency and abundant oxygen vacancies on the surface contribute to the Fe3+/Fe2+ cycle, thereby improving the PMS activation efficiency. The results of free radical quenching and trapping experiments showed that the active species that played a major role in the degradation of HA by photo-Fenton-like were 1O2 and h+. In addition, the photocatalyst still maintains a removal rate of about 87 % after 5 cycles of repeated use, which means that the prepared sample has good reusability and stability. This work provides a method for designing efficient and stable photocatalysts by constructing heterojunctions and oxygen vacancy regulation strategies. •Fe-g-C3N4/MoO3-x photocatalyst can effectively activate persulfate to degrade humic acid (HA).•The optimized Z-type pairing of Fe-g-C3N4 and MoO3-x improves the photo-Fenton-like efficiency.•The Z-scheme heterojunction enhances the separation efficiency of photogenerated e- and h+.•1O2 and h+ are the main active species of FCNM-8 / PMS photo-Fenton-like system under visible light conditions.