A high-efficiency electrochemical sensor of dopamine based on WS2 nanosheets decorated with dandelion-like platinum-silver nanoparticles

Tungsten disulfide nanosheets(WS2) and dandelion-like platinum-silver nanoparticles(PtAg NCs) were synthesized by hydrothermal method and seed-mediated growth approach, and a novel dopamine(DA) electrochemical sensor based on PtAg/WS2/GCE was developed and a new method for detecting DA was established. The investigation of scanning electron microscopy (SEM) and transmission electron microscopy(TEM) exhibited that dandelion-like PtAg NCs were successfully dispersed on the surface of WS2 nanosheets with the size about similar to 10 nm and the thickness of WS2 nanosheet could be estimated to be 3.1 +/- 0.02 nm with a lattice constants of 0.6 +/- 0.03 nm, X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) patterns proved PtAg exists as alloy form and both were metallic phases. The electrochemical results revealed the obtained sensors possessed ideal electrocatalytic activity toward DA with a wide linear range of 0.6 mu M to 1 mM(R-2 = 0.9991), high sensitivity (348.8 mu A.mM(-)(1).cm(-2)), low detection limit 0.2 mu M (S/R = 3), the relative standard deviation (RSD) was estimated to be 2.3%, current respond toward DA remains 92.79% after several day, showing a good stability, repeatability and selectivity. Moreover, compared with other similar DA sensors, the linear range of the sensor was 2 orders of magnitude wider, and the detection limit was 5 times lower.