Ammonia gas sensing properties and density functional theory investigation of coral-like Au-SnSe2 Schottky junction

This paper introduces a coral-like Au-modified SnSe2 nanocomposite prepared by a simple hydrothermal method. The pure- and Au-modified SnSe2 film sensors were prepared on the substrate with interdigitated electrodes by drop coating. The compositions, morphologies and microstructures of the as-synthesized nanomaterials were observed using transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The Au-modified SnSe2 nanocomposite has a coral-like morphology assembled from many irregular and very thin nanosheets. The gas performances of the film sensors at room temperature were tested through a series of experiments. The experimental results demonstrated that the Au-modified SnSe2 nanocomposite film sensor had excellent response characteristics, extremely short response/recovery time, outstanding gas selectivity and stability towards ammonia gas compared with the pure one. In addition, the first-principle density functional theory (DFT) was employed to simulate the effect of Au modification on gas adsorption behavior, clarifying the internal mechanism of gas sensing by combining with Au-SnSe2 Schottky junction. These results verified that the Au-modified SnSe2 film sensor is a high-performance candidate for enhanced ammonia gas sensing properties at room temperature.