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 3, 3, 150 degrees C. Doping of In2O3 with La increases its response towards H2S and La3+ (5.0 wt.% La2O3)-doped In2O3 showed the maximum response at 125 degrees 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. (C) 2008 Elsevier Ltd. All rights reserved.