Synergy between Iron and Selenide on FeSe2(111) Surface Driving Peroxymonosulfate Activation for Efficient Degradation of Pollutants

In this study, iron selenide nanoparticles (FeSe2) were synthesized and applied in Fenton-like reactions for degradation of pollutants. It was found that FeSe2 exerts excellent catalytic reactivity toward different oxidants including peroxymonosulfate (PMS), peroxydisulfate, and H2O2, which can degrade a wide range of pollutants such as 2,4,4′-trichlorobiphenyl, bisphenol A, sulfamethoxazole, chlortetracycline, and perfluorooctanoic acid, with the degradation efficiency and TOC removal of pollutants reaching 55–95 and 20.3–50.9%, respectively. The mechanism of PMS activation by FeSe2 was elucidated, and the synergistic effect between Fe and Se for PMS activation was discovered to be the dominant catalytic mechanism, as evidenced by free-radical quenching, electron paramagnetic resonance, and density functional theory studies. Briefly, the Fe(II) site on the FeSe2 surface (111) accounted for PMS activation, while the reducing Se species on the surface not only acted as an electron donor contributing to Fe(II) regeneration but also produced Se vacancies further facilitating Fe(II) regeneration to improve the performance of PMS activation. In addition, FeSe2 exhibited high catalytic activity and stability for PMS activation with different pH, and can degrade PCBs efficiently in the presence of anions, natural organic matter water matrices or in complex soil eluents. This study presents the development and evaluation of FeSe2 as a novel and highly efficient activator that exhibits promise for practical applications for the degradation of pollutants in wastewater and soil wash eluent with Fenton-like reactions.