Rapid detection of HS gas driven by the catalysis of flower-like α-BiMoO and its visual performance: A combined experimental and theoretical study.

Metal oxide semiconductor (MOSs) are attractive materials for the development of HS gas sensors. However, detecting HS with short response and recovery times while also lowering the limit of detection to sub-ppb levels remains a significant challenge. We therefore developed flower-like α-BiMoO microspheres for HS gas detection that provide fast response and recovery times (3 and 22 s, respectively, for 100 ppm HS), while also reducing the limit of detection to 1 ppb. The sensor performs well in terms of sensitivity, reproducibility, long-term stability, including humidity stability. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations revealed that HS dissociates readily on the reduced α-BiMoO surface and that Mo plays a catalytic role, accelerating the rate of HS decomposition and enabling a fast response. Moreover, test strips containing α-BiMoO were also prepared, which enabled the naked eye detection of ppm-level HS gas at room temperature; a light-yellow to orange to brown color change occurs when exposed to HS, due to its conversion into stable sulfides. This work expands the application of α-BiMoO to HS gas sensing, and provides a strategy for the use of MOSs as sensor materials for the detection of other gases.