Significantly enhanced temperature-dependent selectivity for NO2 and H2S detection based on In2O3 nano-cubes prepared by CTAB assisted solvothermal process

It is a huge challenge to develop a highly precision sensor with good selectivity for target gas. In this work, In2O3 nano-cubes, prepared using a cetyltrimethyl ammonium bromide assisted solvothermal process, were used to make gas sensors for H2S and NO2 detections. The In2O3 nano-cube based sensor exhibited a good temperature-dependent selectivity toward H2S and NO2. At room temperature of 25 degrees C, the sensor exhibited a good selectivity towards H2S with a high response (1461 for 60 ppm H2S), fast response/recovery times (82 s/102 s) and a superior detection limit (0.005 ppm). Whereas at an operation temperature of 100 degrees C, the sensor showed a poor sensitivity to H2S, but an excellent selectivity towards NO2 with high response (336 for 100 ppm NO2), fast response/recovery times (18 s/31 s) and a superior detection limit (0.001 ppm). The sensor also showed good reversibility, reproducibility and long-term stability at two optimized operation temperatures. The different sensing mechanisms for H2S and NO2 were discussed and the temperature dependent selectivity was explained. (C) 2019 Elsevier B.V. All rights reserved.