Synthesis, characterization and field emission studies of NiO-rGO nanocomposite

In this work, NiO-rGO nanocomposite was synthesized by hydrothermal/solvothermal method on nickel foil. The as-synthesized product was subjected to various characterizations such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Raman spectroscopy, in order to reveal its phase, morphology and structure. The SEM analysis reveals formation of nearly vertically oriented and randomly distributed nanoflakes of NiO-rGO nanocomposite on entire substrate surface. The Raman spectrum of the NiO-rGO composite showed characteristic D and G bands of rGO, confirming its presence in the composite. The NiO-rGO composite emitter showed promising field emission behaviour. The values of turnon and threshold fields, defined at emission current density of 1 and 10 mA/cm2, were observed to be 1.8 and 2.25 V/mm, respectively, which are comparable to alike composite emitters. Furthermore, from the NiO-rGO composite emitter, maximum current density of 719 mA/cm2 has been extracted at an applied field of 4.5 V/mm. The observed results imply potential of NiO-rGO composite emitter for application in vacuum microelectronic devices.