Nanocrystalline In2O3–SnO2 thick films for low-temperature hydrogen sulfide detection

Nanocrystalline In2O3–SnO2 thick films were fabricated using the screen-printing technique and their responses toward low concentrations of H2S in air (2–150 ppm) were tested at 28–150 °C. The amount of In2O3-loading was varied from 0 to 9 wt.% of SnO2 and superb sensing performance was observed for the sensor loaded with 7 wt.% In2O3, which might be attributed to the decreased crystallite size as well as porous microstructure caused by the addition of In2O3 to SnO2 without structural modification. The interfacial barriers between In2O3 and SnO2 might be another major factor. Typically, the response of 7 wt.% In2O3-loaded SnO2 sensor toward 100 ppm of H2S was 1481 at room temperature and 1921 at optimal operating temperature (40 °C) respectively, and showed fast and recoverable response with good reproducibility when operated at 70 °C, which are highly attractive for the practical application in low-temperature H2S detection.