Amorphous molybdenum sulfide nanosheets composed of [Mo3S13]2- active-site motifs for enhancing conversion of Fe3+/Fe2+ in Fenton reaction under neutral condition

Abstract

Molybdenum disulfide (MoS2) edges have been considered as effective active sites to promote Fenton reaction, whereas the basal plane is inert. It is dauntingly challenging to maximally exposure edge active sites and active the basal plane. Inspired that [Mo3S13]2- clusters is basic structural unit of MoS2 edge, amorphous molybdenum sulfide (a-MoSx) nanosheets composed of [Mo3S13]2- active-site motifs may be an ideal co-catalyst for Fenton reaction. Herein, accordion-like a-MoSx nanosheets were successfully designed and prepared by one step oil-heating method. The as-synthesized a-MoSx exhibited superior activity in co-catalytic Fenton degradation of tetracycline (TC, 10 mg/L) than that of MoS2, which could reach 94.73 % within 5 min under neutral condition. This is attributed to the better Mo-S coordination mode or surrounding environment to accelerate the rate-limiting step of Fe3+/Fe2+ conversion, with DFT calculations indicating for Fe3+ on Mo4+ or S2-/S22- sites in a-MoSx a higher electron aggregation density and lower adsorption energy. Impressively, all the S atoms in a-MoSx have low adsorption energy with H atom, making that the co-catalytic Fenton reaction can be performed under neutral conditions. For a scale-up experiment, 5 L of TC wastewater (50 mg/L) was almost completely degraded after 120 min in the nickel foam/a-MoSx + H2O2 + Fe2+ system.