凝膠衍生P/Si-TiO2薄膜之相穩定性與光催化性質

Abstract

The P/Si-TiO2 thin films, with a molar ratio [P+Si]/[P/Si-TiO2]=0.03, were synthesized by the sol–gel method and spin-coating technique. Effects of relative ratios of dopants (i.e., R≡[P]/([ P+Si]) and calcination temperatures on phase transformation, grain growth, film thickness, surface morphology, light transmittance, energy gap and photocatalytic activity of the gel-derived P/Si-TiO2 thin films were examined and their results were compared with those of the undoped TiO2 thin films. By simultaneously doping Si and P elements into the Ti-O framework, the P/Si-TiO2 (i.e., 0.33≤ R ≤0.67) thin films calcined at ≦900℃ adhered strongly to the surface of fused-silica substrate and were composed of anatase-TiO2 only. The photocatalytic activities of the thin films were measured and represented using a characteristic time constant (τ) for the MB degradation. The small τ stands for high photocatalytic ability. The P/Si-TiO2 thin film prepared at R = 0.5 and 800℃ gave the best photocatalytic activity; this thin film decomposed about 90 mole% of MB in the water (the corresponding τ = 5.7 h), after 365-nm UV light irradiation for 12 h.