Rapid detection of H2S gas driven by the catalysis of flower-like α-Bi2Mo3O12 and its visual performance: A combined experimental and theoretical study

Metal oxide semiconductor (MOSs) are attractive materials for the development of H2S gas sensors. However, detecting H2S 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-Bi2Mo3O12 microspheres for H2S gas detection that provide fast response and recovery times (3 and 22 s, respectively, for 100 ppm H2S), 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 H2S dissociates readily on the reduced α-Bi2Mo3O12 surface and that Mo plays a catalytic role, accelerating the rate of H2S decomposition and enabling a fast response. Moreover, test strips containing α-Bi2Mo3O12 were also prepared, which enabled the naked eye detection of ppm-level H2S gas at room temperature; a light-yellow to orange to brown color change occurs when exposed to H2S, due to its conversion into stable sulfides. This work expands the application of α-Bi2Mo3O12 to H2S gas sensing, and provides a strategy for the use of MOSs as sensor materials for the detection of other gases.