CICECO » Solid-Gas Phase Photo-Catalytic Behaviour of Rutile and TiOn (1 < n < 2) Sub-Oxide Phases for Self-Cleaning Applications

authors	Nuno, M; Adamaki, V; Tobaldi, DM; Gallo, MJH; Otero-Irurueta, G; Bowen, CR; Ball, RJ
nationality	International
journal	MATERIALS
author keywords	photocatalysis; TiO2; sub-oxide
keywords	CARBON-DIOXIDE; TITANIUM-DIOXIDE; PHOTOCATALYTIC REDUCTION; WATER; PERFORMANCE; GEL; CO2; NANOPARTICLES; TI3+; BLUE
abstract	The solid-gas phase photo-catalytic activities of rutile TiO2 and TiOn (1 < n < 2) sub-oxide phases have been evaluated. Varying concentrations of Ti3+ defects were introduced into the rutile polymorph of titanium dioxide through carbo-thermal reduction at temperatures ranging from 350 degrees C to 1300 degrees C. The resulting sub-oxides formed were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, impedance spectroscopy and UV-visible diffuse reflectance spectroscopy. The presence of Ti3+ in rutile exposed to high reduction temperatures was confirmed by X-ray diffraction. In addition, a Ti3+-TI4+ system was demonstrated to enhance the photo-catalytic properties of rutile for the degradation of the air pollutants NO2 and CO2 under UV irradiation of wavelengths (A) 376-387 nm and 381-392 nm. The optimum reduction temperature for photo-catalytic activity was within the range 350-400 degrees C and attributed to improved charge-separation. The materials that were subject to carbo-thermal reduction at temperatures of 350 degrees C and 400 degrees C exhibited electrical conductivities over one hundred times higher compared to the non-reduced rutile. The results highlight that sub-oxide phases form an important alternative approach to doping with other elements to improve the photo-catalytic performance of TiO2. Such materials are important for applications such as self-cleaning where particles can be incorporated into surface coatings.
publisher	MDPI
issn	1996-1944
year published	2019
volume	12
issue	1
digital object identifier (doi)	10.3390/ma12010170
web of science category	Materials Science, Multidisciplinary
subject category	Materials Science
unique article identifier	WOS:000456410200170