An advanced TiO2/Fe2TiO5/Fe2O3 triple-heterojunction with enhanced and stable visible-light-driven fenton reaction for the removal of organic pollutants

The construction of catalysts with high efficiency and stability for heterogeneous Photo-Fenton reaction Heterogeneous (PFR) has been a major challenge for the degradation of organic pollutants. Here, we successfully develop an advanced TiO2/Fe2TiO5/Fe2O3 triple-heterojunction structure by using the mesoporous TiO2 spheres as the substrate via a simple ion-exchange method. The XRD and HRTEM results demonstrate the generation of Fe2TiO5 on the interface between TiO2 and Fe2O3, which can be used as a bridge to transfer the photo-excited electrons from TiO2 to Fe2O3. The as-prepared triple-heterojunction has abundant interphase boundaries which greatly improve the migration of photo-excited charges among different components. As a result, the prepared triple-heterojunction has a significantly enhanced PFR activity for the visible-light-driven degradation of methyl orange (MO) and colorless organic pollutant of phenol, compared with the single catalysts of Fe2O3 and TiO2, and the binary-heterojunction of TiO2/Fe2O3. Compared to the traditional Fe2O3 based PFR, the degradation rates of MO and phenol over triple-heterojunction can be increased from 4% to 87% within 10 min irradiation and from 38% to 100% within 60 min irradiation, respectively. And the total organic carbon (TOC) degradation rate of phenol can be up to 85%. Moreover, this advanced triple-heterojunction has a wide pH value range of application in PFR. Either at a pH of 4.0 or 7.0, it shows a much higher and more stable PFR activity for the degradation of MO than the catalysts of Fe2O3 and TiO2/Fe2O3. And the reaction rate of TiO2/Fe2TiO5/Fe2O3 almost keeps changeless even after 10th cycles, suggesting its vast application foreground in the environmental pollutant treatment. (C) 2017 Elsevier B.V. All rights reserved.