MoS2 as a cocatalyst applied in advanced oxidation processes for enhancing degradation of organic pollutants: a review

Fenton technology, as a typical advanced oxidation processes (AOPs), can generate reactive oxygen species (ROS) of strong oxidation capacity to degrade organic pollutants, which has attracted wide attention. However, it is accompanied by the slow Fe3+/Fe2+ cycle rate, easy to generate iron sludge and so on. Recently, it has been proven that the inorganic cocatalysts represented by MoS2 can effectively solve the above problems. Meanwhile, MoS2 can accelerate the activation of peroxymonosulfate (PMS) and peroxodisulfate (PDS) by Fe2+. In this paper, MoS2 as the cocatalyst in H2O2 + Fe2+, PMS + Fe2+ and PDS + Fe2+ were comprehensively reviewed. Specially, the cycling processes of Fe3+/Fe2+ in different systems, the cocatalytic effect of MoS2 by the exposed active sites, the ROS generation mechanism as well as the microscopic mechanism during the reaction were elaborated emphatically. The results indicate that the reductive active sites on the surface of MoS2 can promote the regeneration of Fe2+ through the cycle between Fe3+/Fe2+ and Mo4+/Mo5+/Mo6+. Thus, ROS such as ⋅OH, SO4⋅− and 1O2 with strong oxidizing property can be produced to improve the degradation efficiency of organic pollutants. At last, the challenges and developments of MoS2 cocatalysts in AOPs for practical applications were prospected. This review contributes to a deeper understanding of the cocatalytic effect of two-dimensional metal sulfides in AOPs and facilitates their industrial application.