Development of High-Performance Bismuth Sulfide Nanobelts Humidity Sensor and Effect of Humid Environment on its Transport Properties

[Image: see text] Orthorhombic phase bismuth sulfide (Bi(2)S(3)) nanobelts were prepared via liquid–solid phase reaction method. Bi(2)S(3) nanobelts were observed to be preferentially oriented along the (101) plane. Direct band gap (2.95 eV) and characteristic wavelength (λ(max) = 342 nm) were extracted through UV–visible spectroscopy. Specific surface area (9.8 m(2)/g) and pore size (2.5–120 nm) were evaluated through Brunauer–Emmett–Teller (BET) analysis. Relative humidity (RH) sensing properties were studied in the range of 11–97% RH at ambient conditions. The response of the sensor increases linearly with increase in RH. Fast response time (8–10 s) and recovery time (15 s) were observed. Reproducible and large response was also observed between 11 and 97% RH. Small hysteresis (<5%) and long-term stability during 30 days were confirmed. As a function of frequency, capacitance, alternating current conductivity, and electrical complex modulus in the frequency range of 20–2 MHz were studied at 11–97% RH. The sensing mechanism was also studied.