Design and facile one-step synthesis of FeWO4/Fe2O3 di-modified WO3 with super high photocatalytic activity toward degradation of quasi-phenothiazine dyes

For most of WO3, a visible-light-driven photocatalyst, its barrier in photocatalytic degradation is the low conduction band (CB) potential that can not reduce O-2 to O-2(-) center dot and HO2 center dot radicals and thus results in fast recombination of electron/hole. With this in mind, a new active FeWO4/Fe2O3 di-modified WO3 was designed and prepared via by a straightforward but effective strategy by introducing of FeWO4 and Fe2O3 clusters (or nanoparticles) on WO3. The performance of di-modified WO3 showed super high photocatalytic activity in degrading quasi-phenothiazine dyes of Methylene blue (MB), Toluidine blue (TB), Azure I (AI) and Acridine orange (AO) under visible light irradiation, and the corresponding k values are 5.3, 4.4, 3.8 and 5.8 times larger than that of pure WO3, respectively. This improvement was mainly due to the fact that photoexcited electrons can migrate to the matching CB of firmly and highly dispersed FeWO4 and Fe2O3, then be consumed rapidly by a valence decrease from Fe3+ to Fe2+ and Fenton reaction between Fe2+ and H2O2. And the strong adsorption of Fe species toward N and S (or N) elements in quasi-phenothiazine dyes, also positively promoted the efficiency of degradation.