Ferroelectric SbSI nanowires for ammonia detection at a low temperature

For the first-time, an ammonia (NH₃) gas sensor has been fabricated using antimony sulfoiodide (SbSI). A few aligned SbSI nanowires have been bonded to Au microelectrodes on a glass substrate. The fabricated sensor has been tested for various concentrations of NH₃ in N₂ at operating temperatures below (T = 280 K) and above (T = 304 K) Curie point of SbSI. A significantly higher response and sensitivity of the sensor is observed, when the operating temperature is lower than Curie temperature. However, comparable values of the low detection limits (6.0 ± 2.4) ppm and (6.3 ± 3.9) ppm have been determined at operating temperatures of 280 K and 304 K, respectively. The current response, as well as the sensitivity versus ammonia concentration, follow the power laws known for conductometric gas sensors. SbSI nanosensor exhibits good stability, short term response reversibility, and does not require a heating system for recovery. This device also demonstrates a high selectivity to NH₃ against other interfering gases. The ammonia sensing mechanism has been explained by considering the formation of NH₄ ⁺ ions on the nanowire surface and the occurrence of proton transfer according to Grotthuss's chain reaction.