Fast, Sensitive, and Selective Hydrogen Sensing of Silver-Doped Bismuth Sulfide Nanobelts

We report the synthesis, characterizations, and hydrogen gas sensing of pure and silver (Ag)-doped bismuth sulfide (Bi₂S₃) nanobelts. The economical synthesis of Bi₂S₃ was carried out by the sulfurization of bismuth oxide (Bi₂O₃) using conventional solid-state reaction method. X-ray diffraction and scanning electron microscopy confirmed the synthesis of pure and silver-doped Bi₂S₃ nanobelts. Hydrogen gas sensing was studied at room temperature through current–voltage (I–V) characteristics. The percentage response of pure Bi₂S₃ nanobelts was 4.10%, whereas 2.5% silver-doped Bi₂S₃ showed a response of 24.01% at 26.66 kPa of H₂ pressure. Response and recovery times were also analyzed from the dynamic response curves. Pure Bi₂S₃ nanobelts showed a response time of 8 s and recovery time of 20.4 s, whereas 2.5% silver-doped Bi₂S₃ nanobelts showed a response time of 6 s and recovery time of 15.2 s. The silver doping improved the reproducibility, selectivity, and stability of the sensor.