A low operating temperature and high performance sensor for H2S detection based on α-Fe2O3/TiO2 heterojunction nanoparticles composite

Firstly, a low operating temperature and high performance sensor for H2S detection based on α-Fe2O3/TiO2 heterojunction nanoparticles (NPs) was developed by a liquid phase reaction with low synthesis temperature. Secondly, the microstructures and chemical compositions of the gas sensing material were analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscope, energy dispersive spectrometer and X-ray photoelectron spectra methods. Thirdly, with the 50 mol% α-Fe2O3 doping amount and operating temperature of 120 °C, the gas sensing performances of the developed α-Fe2O3/TiO2 NPs composite sensor to H2S were obtained: the responses of 3.4–15.6 to 1–50 ppm H2S, a linear relationship between the sensor response and the H2S concentration, the acceptable response/recovery time of 25 s and 48 s to 50 ppm H2S, excellent selectivity (10 times higher than those of the other tested gases) to H2S, and good repeatability and stability in 1-month duration. These excellent H2S gas sensing performances were attributed to the effects of n–n heterojunctions of two metal oxides, which were discussed in detail. Finally, the superior performances of the developed α-Fe2O3/TiO2 NPs composite sensor were compared with the other reported H2S sensors, which the low operating temperature of 120 °C was highlighted.