Room temperature H₂S gas sensing properties of In₂O₃ micro/nanostructured porous thin film and hydrolyzation-induced enhanced sensing mechanism

The micro/nanostructured orderly porous In₂O₃ ultrathin film and its gas sensing devices are fabricated via the solution-dipping monolayer organic colloidal template. Such In₂O₃ thin film is of about 200 nm in the apparent thickness and ordered porous structure. The porous In₂O₃ film-based sensor has exhibited ultrahigh response to H₂S at room temperature, more than two orders of magnitude higher than the previously reported highest value. Further experiments have demonstrated that the ambient humidity plays a crucial role in the ultra-highly enhanced gas sensing to H₂S at room temperature. A sensing mechanism based on ambient humidity-induced H₂S hydrolyzation is presented, including hydrolyzation-induced desorption of the chemisorbed oxygen and formation of water thin film on the In₂O₃ surface, which can well explain the ultrahigh sensing of In₂O₃ to H₂S at room temperature. An In₂O₃-based gas sensor array is thus designed for quantitative detection of H₂S in the real environment with common interferential gases. This work gives a systematic and deep study of the humidity effects on responses of the In₂O₃-based sensors to H₂S, and reveals the sensing mechanism of In₂O₃ films to H₂S at room temperature, indicating practical significance in designing and fabrication of the In₂O₃ film-based H₂S sensors.