The Effect of Fuel Ratio on Photoactivity of Suspension Flame Sprayed Coatings

The photocatalytic properties of titania are widely known. Potential applications include water disinfection or hydrogen production (water splitting) using solar energy, and anti-bacterial surfaces. In this work conformal TiO₂ coatings were deposited using suspension flame spraying. Aqueous titania suspensions (ca 5 wt%) were injected into an acetylene flame (ca 3100 ^oC) via an atomiser. The coatings were adherent with a majority anatase phase composition and retained their nanostructure after coating. The acetylene/oxygen ratio was altered and the photoactivity of the resultant coatings determined by photocurrent generation under illumination. All of the coatings produced were shown to be photoactive, with a marked difference in photocurrent observed between coatings produced with varying flame conditions. Photocurrent generation increased up to 3.7 times with decreasing fuel ratio; this difference was attributed to the build-up of reduced titania species in the coating.