Ultrasensitive NH3 sensor based on Ag3PO4&nano-Ag co-modified SnS with humidity compensation

Abstract

Stannous sulfide (SnS), a representative of two-dimensional (2D) layered monosulfide, shows a broad application in gas sensing due to its unique honeycomb-folded geometry and sensing capability at room temperature. However, the weak response of pure SnS to NH3 and poor humidity resistance limit its gas-sensing application in certain special scenarios like breath analysis. Herein, we propose a co-modulation strategy of combining special heterogeneous design and nano-Ag modification to construct novel nanocomposite of Ag3PO4&Ag@SnS, effectively improving the NH3-sensitive performance of SnS under high humidity conditions. Gas-sensing measurements indicate that the prepared Ag3PO4&Ag@SnS sensor had a low detection limit of 6.73 ppb and showed a 6.17-flod higher response to 10 ppm NH3 than that of pure SnS. It also showed an excellent humidity resistance, as evidence that the response value to10 ppm NH3 at 97% RH is 84.03% of that at 10% RH. The NH3-sensitive enhancement and anti-humidity mechanisms were clarified from heterostructure effects and first-principles calculations, respectively. Finally, to achieve accurate NH3 concentration measurement in high humidity environments, a Genetic Algorithm optimized Back Propagation (GA-BP) neural network algorithm was performed to humidity-compensate the sensors. This study provides an effective strategy to explore applications for accurate NH3 detection in high humidity environments.