Highly sensitive NO2 gas sensor of ppb-level detection based on In2O3 nanobricks at low temperature

Abstract The brick-like In2O3 nanomaterials were synthesized by oil bath precipitation and subsequent calcination method without any templates or surfactants. Technologies of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were carried out to characterize the morphological and structural of the In2O3 samples. Photoluminescence spectra (PL) and X-ray photoelectron spectroscopy (XPS) were used to illustrate the influence of material surface states and internal defects on gas-sensing properties. The In2O3 nanomaterials annealed at 400 °C exhibited a high response (402) toward 500 ppb NO2 with the fast response/recovery time (114 s/49 s) at rather low operating temperature of 50 °C. Besides, it had a good linear relationship in the range of 100–500 ppb. Such excellent gas sensing properties could be on account of the relative large surface area, abundant adsorbed oxygen and good electrical properties.