Engineering low-valence Mo+ (0<<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 Mo delta+ (0 < delta < 4) was prepared. Benefiting from the powerful reduction capacity of Mo delta+, 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 center dot 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 reac-tion). 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 Mo delta+ and photoin-duced 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.