PLD and RF discharge combination used for preparation of photocatalytic TiO2 layers

Abstract

Utilizing pulsed laser deposition technique combined with the radio-frequency discharge (between the target and the substrate), we were able to grow polycrystalline titanium dioxide layers (anatase, rutile) at substrate temperatures 85°C and 150°C. Besides the discharge no additional substrate heating was applied. The layers were prepared from pure titanium and titanium dioxide targets. To optimize deposition conditions, the oxygen background pressure, fluence (from 2Jcm−2 to 9Jcm−2), and discharge power were varied. Silicon wafers (111), fused silica, and polyethylene tubes were used as substrates. The layers’ crystalline structure was determined by X-ray diffraction. Atomic force microscopy was used to characterize the surface properties. Two methods were implemented to determine TiO2 photocatalytic characteristics: 4-chlorphenol solution degradation evaluated by pH measurement and the decomposition of Oleic acid evaluated by the change of the water contact angle on the surface layer. Both methods indicated similar results: the highest photoactivity was observed on the layers consisting from anatase phase and mixture of anatase and rutile.