Self-assembly of TiO2/polypyrrole nanocomposite ultrathin films and application for an NH3 gas sensor

TiO2/polypyrrole (PPy) nanocomposite ultrathin films for NH3 gas detection were fabricated by the in situ self-assembly technique. The films were characterized by UV–Vis absorption, FT–IR spectroscopy, and atomic force microscopy (AFM). The electrical properties of TiO2/PPy ultrathin film NH3 gas sensors, such as sensitivity, selectivity, reproducibility, and stability were investigated at room temperature in air as well as in N2. The results showed that the optimum gas-sensing characteristics of TiO2/PPy ultrathin film were obtained in the presence of 0.1 wt% colloidal TiO2 for 20-min deposition. Compared with pure PPy thin-film sensors, the TiO2/PPy film gas sensor has a shorter response/recovery time. It was also found that both humidity and temperature had an effect on the operation of the TiO2/PPy film gas sensor at low NH3 concentrations.

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