Magnesium incorporation-mediated formation of oxygen vacancies in zinc ferrite for PMS activation toward effective photocatalytic 4-nitrophenol degradation

[Display omitted] •Magnetic ZnFe2O4 NPs were prepared by cost-effective microwave synthesis process.•Mg incorporation into ZnFe2O4 structure promotes the generation of oxygen vacancies.•ZnFe2O4 bandgap increased with Mg incorporation.•Oxygen vacancies play an important role in the photocatalytic degradation of 4-nitrophenol. Developing highly effective heterogeneous photocatalysts for activating peroxymonosulfate (PMS) in the photodegradation of chemical effluents remains challenging. In this study, ZnFe2O4 (ZFO) nanoparticles (NPs) incorporated with different magnesium ratios were prepared using a cost-effective microwave process. The resulting Mgx:ZFO catalysts were characterized by several analysis techniques, and the effect of Mg incorporation on the photocatalytic 4-nitrophenol (4-NP) degradation was studied. The results revealed that incorporating Mg into the ZFO structure substantially improved the photocatalytic removal efficiency of 4-NP from 62 % to 89 %. Compared with pure ZFO, Mg:ZFO contained more surface oxygen vacancies (SOVs), which can facilitate the generation and transfer of photocarriers, promote PMS activation, and improve photocatalytic performance. The ZFO catalysts exhibited larger surface areas after Mg incorporation, which provided more active sites for 4-NP removal. Finally, the bandgap energy of ZFO was widened from ∼ 1.67 eV to ∼ 1.80 eV after Mg incorporation, which could reduce photocarrier recombination and result in higher photocatalytic removal efficiency.