In this study, we focused on the synergistic enhancement in the field emission performance of MgO/r-GO hybrid nanostructures, supported by a comprehensive correlation between experimental observation and density functional theory (DFT) analysis. Structural investigation by X-ray diffraction (XRD) refinement confirms the cubic rock-salt phase of MgO and the successful integration of r-GO (2θ = 24.2°). Raman spectra of the composites indicate the signature D, G, and 2D bands of r-GO, with two minor defect-induced vibrational bands at 277 cm–1 and 442 cm–1 of Mg(OH)2. The Fourier transform infrared (FTIR) spectra elucidate the chemical bonding and functional groups, while UV-DRS spectra exhibit a bandgap modulation from 5.24 to 3.02 eV due to the strong hybridization. Morphological analysis using field emission scanning electron microscopy (FESEM) demonstrates a dispersed network of MgO nanoparticles on r-GO sheets, which offers a high surface area and efficient emission sites. The MgO/r-GO hybrid nanostructure exhibits enhanced field emission performance, evidenced by a lower turn-on field (2.4 V/μm @ 1 μA/cm2), increased emission current density (1845 μA/cm2 @ 6.7 V/μm), and preliminary indication of long-term stability over a long period of ∼4 h, due to improved electrical conductivity, a reduced work function, and effective charge transfer at the MgO/r-GO interface. The DFT study determined the local work function (φ) to be ∼5.01 eV for MgO and ∼4.51 eV for MgO/r-GO composites, and the field enhancement factor (β) was calculated to be 2348 and 3250 for MgO and MgO/r-GO composite field emitters, respectively. The observed density of states indicates charge redistribution near the Fermi level and modifications of the electronic structure, which recommend the potential of MgO/r-GO hybrids for advanced electron emission applications. The experimental and theoretical findings recommend that the MgO/r-GO hybrids are promising for advanced electron-emission applications in vacuum and nanoelectronics.
Karmakar et al. (Thu,) studied this question.