Design of high-performance ternary ammonia gas sensors based on Au NPs hybrid PANI-TiO2 nanocomposites on flexible polyimide substrate

Abstract

Here, an effective and economic ternary ammonia gas sensor with Au nanoparticles (NPs) hybrid polyaniline (PANI)- titanium dioxide (TiO₂) nanocomposites on a flexible polyimide substrate has been successfully fabricated. In this work, high catalytic and controllably synthesized near-spherical Au NPs with size of sub-100 nm was interestingly employed, meanwhile, a facile in-situ oxidative polymerization was used to composite the Au NPs with the conventional binary PANI- TiO₂. Analysis and characterization of the structures, compositions, and the gas-sensing performances of the designed ternary ammonia gas sensor were systematically explored. The results show that the Au and TiO₂ NPs were evenly distributed among the PANI fibrous networks, favoring the construction of the practical gas sensors. Besides, the gas sensor with 1 wt% of Au and 20 mol% of TiO₂ dispersed into PANI showed an excellent gas-sensing performance: the response and recovery rates of the sensors respectively reach 32 s and 111 s to 100 ppm concentration of ammonia at room temperature, and the response value approach to 123%, which is approximately 1.9 times and 1.2 times higher than the pure PANI and PANI-TiO₂. Furthermore, the designed gas sensors exhibited significant stability, selectivity and response-concentration linearity (correlation coefficients R²=0.9984). It is expected that our concerned and designed ternary gas sensors may find great potential applications such as in flexible wearable devices and the medical health monitors.