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 H 2 S detection based on α-Fe 2 O 3 /TiO 2 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-Fe 2 O 3 doping amount and operating temperature of 120 °C, the gas sensing performances of the developed α-Fe 2 O 3 /TiO 2 NPs composite sensor to H 2 S were obtained: the responses of 3.4–15.6 to 1–50 ppm H 2 S, a linear relationship between the sensor response and the H 2 S concentration, the acceptable response/recovery time of 25 s and 48 s to 50 ppm H 2 S, excellent selectivity (10 times higher than those of the other tested gases) to H 2 S, and good repeatability and stability in 1-month duration. These excellent H 2 S 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-Fe 2 O 3 /TiO 2 NPs composite sensor were compared with the other reported H 2 S sensors, which the low operating temperature of 120 °C was highlighted.