High-performance UV-activated room temperature NO 2 sensors based on TiO 2 /In 2 O 3 composite

Porous TiO 2 nanoparticle (NPs)-embedded In 2 O 3 nanofibers (NFs) were synthesized using electrospinning for fabricating room temperature (RT) nitrogen dioxide (NO 2 ) gas sensors. The diameter of the porous polycrystalline TiO 2 /In 2 O 3 nanofibers was 60 nm and they were composed of sub-grains of average size 10–15 nm. Compared to pure In 2 O 3 nanofibers, the TiO 2 /In 2 O 3 nanofibers exhibited higher response, shorter response and recovery times, better reproducibility, and improved selectivity to NO 2 . The response of the TiO 2 /In 2 O 3 composite to 5 ppm NO 2 at RT under ultraviolet (UV) irradiation was 49.29, which was 8.96 times higher than that of pure In 2 O 3 . Even for a high relative humidity (RH) of 80%, the response of the TiO 2 /In 2 O 3 composite to 5 ppm NO 2 was approximately 41.25. The enhanced NO 2 sensing performance of the composite can be ascribed to the formation of the TiO 2 /In 2 O 3 n–n heterojunction, porous structure of the nanofibers, enhanced light absorption, and large number of O vacancies.