Core-shell Au@SiO2 nanocrystals doped PANI for highly sensitive, reproducible and flexible ammonia sensor at room temperature

Herein, we report a facile and straightforward synthetic strategy for preparing flexible NH3 sensors with high performance and application prospects. Interestingly, core-shell Au@SiO2 nanocrystals (NCs) doped polyaniline (PANI) were innovatively employed as the sensitive material and the NH3 sensors were constructed via a simple droplet-evaporation self-assembly process on the polyimide substrates. Experimental results show that the well-designed NH3 sensor with ~ 20 wt% of Au@SiO2 NCs doping PANI exhibited high sensitivity, flexibility and combined reproducibility at room temperature: the device's detection limit of NH(3 )reached a 10 ppb level; the device's concentration deviation induced by large-angle and cycled bending could be kept within 0.6 ppm, and the maximum response variation was less than 2.7% through 30 days of monitoring; Additionally, the designed NH3 sensor does have insusceptibility to the ambient relative humidity (from 48% to 66%). Indeed the sensing mechanism of our NH3 sensor was discussed from the Au@SiO2 NCs doped PANI structure, the crucial role of abundant hydroxyl (-OH) functional groups, and the catalytic activity of Au NPs. Overall, this study demon-strates an alternative and effective pathway to fabricate high-performance and applicable NH3 sensors, which may be conducive to further application for environmental NH3 detection and human kidney disease diagnosis.