Energy-Efficient Field Emission Characteristics of Graphene-Wrapped Zinc Oxide Rods

In this article, the cold emission properties of pure and grapheme-wrapped zinc oxide rods (ZR) have been reported. ZRs were grown on both the silicon as well as on glass substrate via simple wet chemical method using KMnO4-assisted seeding technique as wrapped by graphene sheet using simple spin coating technique. The pure and wrapped samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and Fourier-transformed infrared (FTIR) spectrophotometer. XRD confirms the proper phase formation whereas FESEM shows the uniform wrapping of the ZRs with the graphene sheets. FTIR spectra show considerable changes in bond formation after the sample gets wrapped by graphene. Both the samples show promises toward possibilities for being used cold emitter when the field emission characteristics of the sample were measured in the laboratory assembled field emission set up. Unlike the previous report, the wrapped sample shows almost same emission features except little betterment in turn-on field and enhancement factor compared to pure ZnO. This is believed to be due to local destruction of sharpness of the emission sites, thus field enhancement in the hybrid sample and so it is concluded that to get desirable emission characteristic further modification is necessary.