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 °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 °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.