Ammonia gas sensors based on In₂O₃/PANI hetero-nanofibers operating at room temperature

Abstract

Indium nitrate/polyvinyl pyrrolidone (In(NO₃)₃/PVP) composite nanofibers were synthesized via electrospinning, and then hollow structure indium oxide (In₂O₃) nanofibers were obtained through calcination with PVP as template material. In situ polymerization was used to prepare indium oxide/polyaniline (In₂O₃/PANI) composite nanofibers with different mass ratios of In₂O₃ to aniline. The structure and morphology of In(NO₃)₃/PVP, In₂O₃/PANI composite nanofibers and pure PANI were investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and current-voltage (<i>I</i>-<i>V</i>) measurements. The gas sensing properties of these materials towards NH₃ vapor (100 to 1000 ppm) were measured at room temperature. The results revealed that the gas sensing abilities of In₂O₃/PANI composite nanofibers were better than pure PANI. In addition, the mass ratio of In₂O₃ to aniline and the p-n heterostructure between In₂O₃ and PANI influences the sensing performance of the In₂O₃/PANI composite nanofibers. In this paper, In₂O₃/PANI composite nanofibers with a mass ratio of 1:2 exhibited the highest response values, excellent selectivity, good repeatability and reversibility.