Manipulation of the SnSe2 gas sensing properties via Au nanoparticles decoration

Abstract

Gas sensing devices play a key role in safety production, environment protection and human health. Recently, two-dimensional layered materials with large surface area and flexible optoelectronic properties have been widely used for gas sensor design. One of major concern in this field is the sensitivity and selectivity. Here, we show that the sensitivity and selectivity of SnSe2 gas sensor can be manipulated by Au nanoparticles decoration. By choosing NO2 (electron acceptor) and NH3 (electron donor) as target gas, we reveal that the “space charge layer” at the Au-SnSe2 Schottky junction interface plays a critical role in manipulating the sensitivity and selectivity. For NO2, the “space charge layer” hampers the electron transfer from SnSe2 to molecules, thus depressing the sensitivity. While, the electron transfer direction is the opposite when considering NH3, the “space charge layer” would facilitate the electron transfer, thus greatly improving the sensitivity of NH3. Especially, we show that the Au-decorated SnSe2 manifests a sensitivity about -22% toward 80 ppm NH3, which is about three times larger than that measured on pristine SnSe2 under UV illumination. These findings can not only deep our understanding on the mechanism of SnSe2 gas sensing, but also provide an effective strategy to manipulate the sensitivity and selectivity of SnSe2 detector for high performance and low cost gas sensor design.