Dominant microstructural feature over photocatalytic activity of high velocity oxy-fuel sprayed TiO2 coating

TiO2 photocatalytic coatings were deposited through high velocity oxy-fuel spray using anatase powder and rutile powder as feedstock. The as-sprayed TiO2 coating was composed of anatase phase and rutile phase. The anatase content in the coating was significantly influenced by fuel gas flow and melting condition of spray powder. A high anatase content of 35% was achieved for the coating deposited using rutile powder. The anatase content in the coating deposited using anatase powder reached 55–65%. The as-sprayed TiO2 coating was photocatalytically reactive for degradation of acetaldehyde in air. The photocatalytic activity was influenced by spray conditions. The surface morphology and phase structure of coatings deposited at different spray conditions were investigated to clarify the relationship between the coating microstructure and activity. It is found that the photocatalytic activity is significantly influenced by anatase content and surface area.