Improved photoelectric responses of TiO2 modified with CdS to formaldehyde irradiated by UV light

In this work, photoelectric responses of TiO2 and CdS/TiO2 devices to formaldehyde under UV light irradiation were investigated. Pure TiO2 film was firstly prepared by screen printing and CdS/TiO2 hybrid film by the subsequent successive ionic layer adsorption and reaction process. Fundamental characterizations of the as-prepared samples were measured by X-ray diffraction analysis, field-emission gun scanning electron microscopy, energy dispersive X-ray spectrum and high-resolution transmission electron microscope. Photocurrent measurements were utilized to study the photoelectric properties of the as-prepared devices. In comparison with pure TiO2, CdS modified TiO2 hybrid device exhibited an improved UV-irradiated photoelectric response to formaldehyde. It is attributed to the hybrid structure which could increase the separation and restrain the recombination of photogenerated electron-hole pairs. On the basis of the results, the improved photoelectric response of CdS modified TiO2 should be valuable for the practical applications in fabricating photoelectric gas sensors working at room temperature.