Microstructure of nanostructured TiO₂ coating prepared by atmospheric plasma spraying and its photocatalytic properties

The starting nano-TiO₂ feedstock was agglomerated by spray-drying process. Nano-TiO₂ coatings on transparent glasses were prepared by atmospheric plasma spraying (APS). The variation of the anatase content, porosity and grain size with the arc current is investigated extensively. Result shows that the nano-TiO₂ phase is composed of anatase and rutile phase. The content of anatase in the sprayed coatings decreased and the grain size increased with the arc current increasing, and the porosity first increased and then decreased. As-sprayed nano-TiO₂ coatings obtained at the spraying current of 400 A have the best photocatalytic property due to the synergistic effect of the fractions of anatase phase and the rate of porosity.