A sensitive CsBr/Cs3Bi2Br3I6 heterostructure perovskite gas sensor for H2S detection at room temperature with high stability

In this paper, a new all inorganic lead-free perovskite gas sensor based on CsBr/Cs3Bi2Br3I6 composite was prepared to detect low concentrations H2S gas at room temperature (23 degree celsius). A two-step method of evaporation and subsequent spraying process was adopted, which makes the vertical growing Cs3Bi2Br3I6 nanoplates uniformly coating on the surface of the CsBr microspheres and forming a heterogeneous structure based conductive path way. The gas sensing test results indicate that the sensor shows good selectivity and reliable repeatability for H2S detection with long-term stability over 60 days, and the lowest concentration detected is 0.5 ppm. The sensor shows satisfactory stability in the range of relative humidity from 44 to 83 %. The in-situ diffuse reflectance infrared Fourier transformations spectroscopy (DRIFTs) results confirm the formation and enhancement process of SO asymmetric telescopic vibration peak due to the introduction of H2S gas, supporting the synergistic mechanism of adsorption-desorption and dynamic defect passivation.