H2S sensing properties of La-doped nanocrystalline In2O3

Abstract The nanocrystalline powders of pure and La 3+ -doped In 2 O 3 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 In 2 O 3 exhibited high response towards H 2 S gas at an operating temperature 150 °C. Doping of In 2 O 3 with La 3+ increases its response towards H 2 S and La 3+ (5.0 wt.% La 2 O 3 )-doped In 2 O 3 showed the maximum response at 125 °C. The selectivity of the sensor elements for H 2 S against different reducing gases was studied. The results on response and recovery time were also discussed.