CdS/TiO2 nanocomposite film and its enhanced photoelectric responses to dry air and formaldehyde induced by visible light at room temperature

Abstract

Photoelectric responses of pure TiO2 and CdS/TiO2 nanocomposite devices to dry air and formaldehyde under visible light irradiation at room temperature were investigated in this work. The pure TiO2 film was firstly prepared by screen printing and CdS/TiO2 nanocomposite film by the subsequent SILAR process. XRD, FE-SEM, HR-TEM and UV–vis DRS analysis were employed to examine the fundamental characteristics of as-prepared samples. Photoelectric responses of pure TiO2 device displayed that no obvious photocurrent was observed upon turning the visible light on either in dry air or in formaldehyde. But in contrary to pure TiO2 device, the photoelectric response of CdS/TiO2 nanocomposite device has been obviously enhanced. It is the adding of CdS, which works as a sensitizer, that accounts for the enhanced response and makes the CdS/TiO2 device sensitive to the visible light. Moreover, the CdS/TiO2 nanocomposite device exhibits excellent stability to formaldehyde. The present work does not only shed light on the photoelectric gas sensing properties of TiO2 and CdS/TiO2, but also suggests that the CdS/TiO2 nanocomposite may be a promising material for fabricating visible-light-induced photoelectric gas sensors working at room temperature.