Pt/MoS₂/Polyaniline Nanocomposite as a Highly Effective Room Temperature Flexible Gas Sensor for Ammonia Detection

A Pt/MoS₂/polyaniline (Pt/MoS₂/PANI) nanocomposite is successfully synthesized by the hydrothermal process combined with the in situ polymerization method, and then Pt particles are decorated on its surface. The Pt/MoS₂/PANI nanocomposite is deposited on a flexible Au-interdigitated electrode of a polyimide (PI) film. The flexible sensor exhibits a higher response value and fast response/recovery time to NH₃ at room temperature (RT). It results in 2.32-fold and 1.13-fold improvement in the gas-sensing response toward 50 ppm NH₃ compared to those of PANI and MoS₂/PANI-based gas sensors. The detection limit is 250 ppb. The enhancement sensing mechanisms are attributed to the p-n heterojunction and the Schottky barrier between the three components, which has been confirmed by the current-voltage (I-V) curves. A satisfactory selectivity to NH₃ against trimethylamine (TMA) and triethylamine (TEA) is obtained according to density functional theory (DFT), Bader's analysis, and differential charge density to illustrate the adsorption behavior and charge transfer of gas molecules on the surface of the sensing materials. The sensor retains the excellent sensing response value even under high relative humidity and sensing stability at higher bending angle/numbers to NH₃ gas. Hence, Pt/MoS₂/PANI can be regarded as a promising sensing material for high-performance NH₃ detection at room temperature applied in flexible wearable electronics.