Selectivity of Ti-doped In2O3 ceramics as an ammonia sensor

Nanoscale In2O3 powders doped with titanium were prepared by using InCl3·4H2O as a source matter. The materials doped with Ti4+ ions obviously showed the enhanced selectivity to ammonia sensor, compared with two reducing gases of H2 and CO, in the concentration range of 5–1000 ppm at a low operating current (165 mA, equal to 145 °C). Characterization of the materials was performed by thermal analysis, XRD, BET, FTIR, and magnetic susceptibility measurement. The mechanism of the selective gas sensing is proposed on the basis of the differences in gas molecular structure for adsorption and activation.