Highly dispersed titania-supported iron oxide catalysts for efficient heterogeneous photo-Fenton oxidation: Influencing factors, synergistic effects and mechanism insight

Titania (TiO2) supported iron oxides (Fe-TiO2) are ideal catalysts to be applied in heterogeneous photoFenton oxidation (HPFO) for wastewater treatment because of the capabilities of TiO2 in photocatalysis and iron oxides in interfacial H2O2 activation. It is important to understand the influences of the structural parameters of Fe-TiO2 catalysts and the complicated interplay between TiO2 and iron oxides on the performance of HPFO. In this paper, a series of Fe-TiO2 catalysts are obtained through a facile solid-phase synthesis method. The iron loading content and the calcination temperature are systematically adjusted to tune the crystal phase, size, anatase/rutile ratio and density of oxygen vacancy (OV) site of TiO2, the dispersing state of iron species, and the interfacial structure of the Fe-TiO2 catalysts. Then, the performance of these catalysts in HPFO for degrading methylene blue (MB) are comparatively studied. Correlations between the performance and various structural properties of the catalysts are clarified. The interplay between TiO2 and iron oxides in the HPFO process is elucidated. The insight reaction mechanism is also discussed. Under optimized conditions (an iron loading of 1 wt% and a temperature of 600 degrees C), Fe-TiO2 catalysts with iron lattice doping, well-dispersed ultrasmall alpha-Fe2O3 nanoparticles, appropriate anatase/rutile ratios and abundant OV sites can be obtained. The anatase-rutile-Fe2O3 heterojunction, ultrasmall alpha-Fe2O3 nanoparticles and OV sites in the optimized catalysts work synergistically to improve the charge migration and interfacial activation of H2O2, leading to superior HPFO performance for MB degradation and mineralization. (c) 2020 Elsevier Inc. All rights reserved.

Automated summary

This study investigates the influence of structural parameters of Fe-TiO2 catalysts on the performance of HPFO for wastewater treatment. Optimized Fe-TiO2 catalysts with iron lattice doping, well-dispersed ultrasmall alpha-Fe2O3 nanoparticles, appropriate anatase/rutile ratios, and abundant oxygen vacancy sites show superior performance in degrading methylene blue, attributed to the synergistic effect of anatase-rutile-Fe2O3 heterojunction, ultrasmall alpha-Fe2O3 nanoparticles, and oxygen vacancy sites.