Ag Nanoparticle-Decorated Spindle-Shaped BiVO₄ Nanorods for H₂S Detection

Hydrogen Sulfide (H2S) is a toxic gas and an important biomarker for several common diseases. Therefore, the precise detection of low-level H2S is essential for mitigating harmful gas exposure and pursuing environmental monitoring. In this study, Ag-decorated spindle-shaped BiVO4 (BVO/Ag) with uniform morphology was prepared using a simple hydrothermal and wet impregnation method. Gas-sensing experiments demonstrated that the optimal operating temperature of the BVO/Ag sensor is lowered by 50 °C from that of pristine BiVO4 (BVO), yet achieving a 4-fold increase in the response (Ra/Rg) value, i.e., 31.2 to 50 ppm of H2S at 100 °C. Furthermore, the BVO/Ag exhibits faster response/recovery times (24:27 s), higher selectivity, enhanced signal resolution, and achieves a detection limit of (0.1 ppm). The improved gas sensing performance of the BVO/Ag sensor could be attributed to the chemical sensitization of Ag, which increases charge carrier concentration and adsorbed oxygen leading to a swift charge migration. Moreover, the coarse fibrous structure facilitates gas adsorption by offering multiple active sites for sensing reactions; hence, Ag-decorated BVO spindles with fibrous characteristics exhibit potential as a sensing material in the future.