Ultraviolet irradiation enhanced formaldehyde-sensing performance based on SnO 2 @TiO 2 nanofiber heteroarchitectures

Abstract With the development of society, formaldehyde has gradually become one of the most common air pollutants in urban environments, offices and homes. In this study, the SnO 2 @TiO 2 heterostructure was prepared by an electrospinning technique, in which the TiO 2 nanofibers were uniformly coated by the SnO 2 nanoparticles. Gas sensors were prepared from this material and gas sensing properties against formaldehyde (HCHO) gas were investigated. The SnO 2 @TiO 2 composite with a mass ratio of 1.5:1 (ST-1.5) has good sensing properties for HCHO under UV irradiation. The sensibility of ST-1.5 to HCHO with the concentration of 100 ppm under UV irradiation reaches 18.32, which is much higher than the amount of 4.5 in dark conditions. Also, the response and recovery times are decreased from 20 s to 13 s and 16 s to 9 s by UV irradiation, respectively. Importantly, the response to HCHO in high humidity environments is also enhanced by UV irradiation. The improved gas-sensing properties of the SnO 2 @TiO 2 can be ascribed to an enhanced separation of photogenerated charge electron and hole, which greatly reduces the charge recombination.