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.