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

In this paper, platinum sulfide decorated WS 2 microflakes (PtS/WS 2 ) heterostructure nanocomposites were prepared by an in-situ chemical reduction process. The chemiresistive-type gas sensor based on the synthesized PtS/WS 2 heterostructure nanocomposites exhibited a significantly improved sensing properties compared to that of the pure WS 2 microflakes at different concentration of NH 3 from 1 ppm to 10 ppm at room temperature . As the concentrations of PtS nanoparticles decorated on the surface of WS 2 microflakes increased, the response of the PtS/WS 2 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 WS 2 were significantly improved compared to that pure WS 2 . 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/WS 2 heterostructure, being confirmed by density functional theory (DFT) calculations.