TiO2 photocatalyst in the form of coatings are of many advantages over those in powder form in practical applications. Various processes have been used to form TiO2 coatings including sputtering, Sol-Gel, vapor deposition, thermal spraying, etc. In all those processes, the coatings are deposited under temperatures from 300 to more than 2000 °C. High temperature during those processing may change the microstructure of the as-received TiO2 to a less effective one for photocataltyic performance. In the present study, TiO2 coating was deposited through cold spraying process using two types of powders, which were agglomerated with anatase ultra-fine particles in micro-size and nano-size. Microstructures of both powders and deposited coatings were characterized using X-ray diffraction and scanning electron microscopy. The photocatalytic performance was examined through acetaldehyde degradation under ultraviolet illumination. The results showed that the nanostructured TiO2 coatings were evenly deposited on stainless steel substrate through cold spraying. The thickness of the deposits reached up to 15 µm. The coating presented a rough surface and porous structure. Owing to the low temperature of spray powders, no change occurred to the phase and grain size of TiO2 during deposition process. It was also found that the cold sprayed TiO2 deposits were photocatalytically active for photodegradation of acetaldehyde.

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