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

Abstract

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 NH3 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 demonstrates 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.