Efficient detection of NO2 in Rh-modified SnS/WS2 gas sensor: Structural optimization and sensing performance improvement

Two-dimensional transition metal sulfides (TMDs) have recently emerged as prominent gas-sensing materials, motivated by their exceptional electrical conductivity, distinctive layered structure, and high specific surface area. Building heterostructure and precious metal modification are effective routes to enhance the sensing ability of TMD materials. Nevertheless, the complex preparation procedures and elevated temperatures hinder the construction of the TMD-based heterojunctions. Here, to improve the baseline drift and gas-sensing performance of pure WS2, SnS/WS2 nanostructured materials with various Sn/W ratios (SW3, SW2, and SW1) were designed and prepared via a one-step hydrothermal method to detect NO2 at low temperatures. Subsequently, the sensing performance was further enhanced by modifying the optimized SW2 material with the precious metal Rh. The results indicate that the 1 %Rh-SW2 sensor exhibits a high gas response of 2.83 for 64 ppm NO2 with a fast response/recovery time of 6/33 s at 157 degrees C. The sensor also displays good repeatability and selectivity as well as excellent long-term stability towards NO2 gas. Furthermore, density functional theory (DFT) calculations were exploited to explain the underlying sensing mechanism. In summary, our work presents a promising sensing material for the rapid detection of NO2 through a straightforward synthesis process.