PtS-decorated WS2 microflakes based sensors for selective ammonia detection at room temperature

In this paper, platinum sulfide decorated WS2 microflakes (PtS/WS2) heterostructure nanocomposites were prepared by an in-situ chemical reduction process. The chemiresistive-type gas sensor based on the synthesized PtS/WS2 heterostructure nanocomposites exhibited a significantly improved sensing properties compared to that of the pure WS2 microflakes at different concentration of NH3 from 1 ppm to 10 ppm at room temperature. As the concentrations of PtS nanoparticles decorated on the surface of WS2 microflakes increased, the response of the PtS/WS2 heterostructure sensor to ammonia firstly increased when the concentration of PtS increased up to 1 wt%, whereas above 1%, the response decreased instead. Moreover, it was found that the response speeds of the PtS-decorated WS2 were significantly improved compared to that pure WS2. The sensors also exhibited excellent selectivity to formaldehyde, toluene, acetone, methanol and ethanol at room temperature. The sensing mechanisms were studied by using the in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The enhanced sensing properties could be explained by “electronic sensitization” effect induced by the PtS/WS2 heterostructure, being confirmed by density functional theory (DFT) calculations.