Influence of Cd/S ratio on photocatalytic activity of high‐vacuum‐annealed CdS–TiO₂ thin film

Abstract

CdS–TiO2 thin film heterojunctions were prepared on glass substrates with various Cd/S ratios to optimize the photocatalytic efficiency in UV–visible light irradiation. The CdS underlayer was prepared by the chemical bath deposition technique and subsequently annealed in high vacuum of 5 × 10–5 Pa at 400 °C. The effect of vacuum annealing of the CdS layer on optical and photocatalytic properties of the CdS–TiO2 thin film was also studied. The photocatalytic activity, evaluated by the measurement of the decomposition of methanol in the gas phase under UV–visible light irradiation, shows higher efficiency for a vacuum‐annealed CdS underlayer deposited with Cd/S ratio ≈1:4. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)