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.