Hydrothermal and heat-treated synthesis of SnS nanostructures for VOCs sensing

Two-dimensional chalcogenides have made significant advances as chemiresistive gas sensors due to their high sensing response and low power consumption. However, their inherent morphological complexity, low thermal oxidation temperature, and poor conductivity pose as major obstacles to practical application. In this study, we introduced a synthesis method in combination of hydrothermal reaction and heat treatment to fabricate SnS-based sensing materials with different forms of two-dimensional nanostructure. During preparation, SnS2 with different morphologies were firstly synthesized via hydrothermal reaction, followed by thermal oxidation and nitrogen calcination, flower-like SnS nanostructure, and nanoflake SnS–SnO2 composite, respectively. The samples synthesized by this method demonstrate improved crystallinity, which can overcome the obstacle of poor conductivity. In comparison, the flower-like SnS nanostructure assembled by ultra-thin nanosheets demonstrates improved gas-sensitive performance over nanoflake SnS–SnO2 composite. At the working temperature of 200 °C, the SnS sensor shows a response value as high as 13.3- to 100-ppm ethanol. Besides, the sensor exhibits stable sensing performance and excellent recovery characteristics in response to ethanol. The preparation method proposed in this paper provides an effective approach for the development of high-performance two-dimensional chalcogenide gas sensing materials.