Engineering low-valence Moδ+ (0<δ<4) sites on MoS2 surface: Accelerating Fe3+/Fe2+ cycle, maximizing H2O2 activation efficiency, and extending applicable pH range in photo-Fenton reaction

Fenton/photo-Fenton reaction was limited by slow Fe3+/Fe2+ cycle, low H2O2 activation efficiency, and narrow applicable pH range. Here, Fe atoms doped MoS2 (Fe–MoS2) with abundant of low-valence Moδ+ (0 < δ < 4) was prepared. Benefiting from the powerful reduction capacity of Moδ+, the rate-limiting step of Fe3+ reduction was significantly accelerated. Nearly 100% of H2O2 utilization efficiency was realized. Importantly, 90% of H2O2 was effectively activated to be •OH. As a result, tetracycline degradation rate in photo-Fenton reaction catalyzed by Fe–MoS2 was 5.8 and 4.2 times higher than those of MoS2 and Fe–MoS2-Hyd (prepared by hydrothermal reaction). In comparison with MoS2 and Fe–MoS2-Hyd whose efficient work range were limited in acidic condition, Fe–MoS2 was a pH-universal catalyst (pH = 2.6–14.0) by taking advantage of the exposed Moδ+ and photoinduced electrons, largely improving the environmental tolerance. This work simultaneously addressed three bottlenecks in Fenton/photo-Fenton reaction, and provided a new strategy for the preparation of catalysts with powerful catalytic performance and high environmental adaptability.