Mesoporous Fe-doped TiO2 sub-microspheres with enhanced photocatalytic activity under visible light illumination
Mesoporous Fe-doped TiO2 sub-microspheres (m-Fe-TMS) with high surface area, accessibility, and crystallinity were prepared using a rapid and continuous aerosol-assisted self-assembly (AASA) process for visible-light photocatalytic degradation of persistent pharmaceuticals. The results of X-ray absorption near-edge structure (XANEX) spectroscopy indicate that iron exists as octahedrally coordinated Fe3+ ions substituting Ti4+ in the TiO2 lattice. The similarity of the Fe/Ti ratios in the bulk and on the surface, as determined by energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS), reveals that the substitution of Ti4+ by Fe3+ ions uniformly occurs within m-Fe-TMS. UV–vis diffuse reflectance spectroscopy shows that m-Fe-TMS exhibits a shift in the absorption threshold toward the visible spectrum. Under visible light irradiation, m-Fe-TMS exhibits a maximum rate of pharmaceutical photodegradation four times that of m-TMS. The photocatalytic degradation rates are reproducible with m-Fe-TMS, even after 10 repeated runs. The formation of chemical FeOTi bonds, and not of isolated Fe2O3 particles, leads to the inhibition of photocorrosion and leaching in the photocatalytic reactions. The ease and scalable production of m-Fe-TMS using the AASA process will facilitate the development of visible light-driven photocatalysts for decomposition of environmental contaminants.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A rapid and scalable route to obtain an efficient visible-light-sensitive mesoporous Fe-doped TiO2 sub-microspheres. ► The substitution of Ti4+ by Fe3+ ions uniformly occurs within such mesoporous sub-microspheres. ► The maximum rate of pharmaceutical photodegradation is increased by 4 times.
Journal: Applied Catalysis B: Environmental - Volume 127, 30 October 2012, Pages 175–181