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

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.