Superior Field Emission Properties of Layered WS(2)-RGO Nanocomposites

We report here the field emission studies of a layered WS(2)-RGO composite at the base pressure of ~1 × 10(−8) mbar. The turn on field required to draw a field emission current density of 1 μA/cm(2) is found to be 3.5, 2.3 and 2 V/μm for WS(2), RGO and the WS(2)-RGO composite respectively. The enhanced field emission behavior observed for the WS(2)-RGO nanocomposite is attributed to a high field enhancement factor of 2978, which is associated with the surface protrusions of the single-to-few layer thick sheets of the nanocomposite. The highest current density of ~800 μA/cm(2) is drawn at an applied field of 4.1 V/μm from a few layers of the WS(2)-RGO nanocomposite. Furthermore, first-principles density functional calculations suggest that the enhanced field emission may also be due to an overalp of the electronic structures of WS(2) and RGO, where graphene-like states are dumped in the region of the WS(2) fundamental gap.