H2S sensing properties of La-doped nanocrystalline In2O3

The nanocrystalline powders of pure and La3+-doped In2O3 with cubic structure were prepared by a simple hydrothermal decomposition route. The structure and crystal phase of the powders were characterized by X-ray diffraction (XRD) and microstructure by transmission electron microscopy (TEM). All the compositions exhibited a single phase, suggesting a formation of solid solution in the concentration of doping investigated. Gas-sensing properties of the sensor elements were tested by mixing a gas in air at static state, as a function of concentration of dopant, operating temperature and concentrations of the test gases. The pure In2O3 exhibited high response towards H2S gas at an operating temperature 150 °C. Doping of In2O3 with La3+ increases its response towards H2S and La3+ (5.0 wt.% La2O3)-doped In2O3 showed the maximum response at 125 °C. The selectivity of the sensor elements for H2S against different reducing gases was studied. The results on response and recovery time were also discussed.