High-performance UV-activated room temperature NO2 sensors based on TiO2/In2O3 composite

Abstract

Porous TiO₂ nanoparticle (NPs)-embedded In₂O₃ nanofibers (NFs) were synthesized using electrospinning for fabricating room temperature (RT) nitrogen dioxide (NO₂) gas sensors. The diameter of the porous polycrystalline TiO₂/In₂O₃ nanofibers was 60 nm and they were composed of sub-grains of average size 10–15 nm. Compared to pure In₂O₃ nanofibers, the TiO₂/In₂O₃ nanofibers exhibited higher response, shorter response and recovery times, better reproducibility, and improved selectivity to NO₂. The response of the TiO₂/In₂O₃ composite to 5 ppm NO₂ at RT under ultraviolet (UV) irradiation was 49.29, which was 8.96 times higher than that of pure In₂O₃. Even for a high relative humidity (RH) of 80%, the response of the TiO₂/In₂O₃ composite to 5 ppm NO₂ was approximately 41.25. The enhanced NO₂ sensing performance of the composite can be ascribed to the formation of the TiO₂/In₂O₃ n–n heterojunction, porous structure of the nanofibers, enhanced light absorption, and large number of O vacancies.