Uncovering the origin of enhanced field emission properties of rGO–MnO2 heterostructures: a synergistic experimental and computational investigation - data

Herein, we report the synthesis of MnO₂ nanorods and rGO/MnO₂ nano-heterostructure using low-cost hydrothermal and modified Hummer’s methods, respectively. Detailed characterization and confirmation of the structural and morphological properties are done via X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Transmission Electron Microscopy (TEM). Compared to the isolated MnO₂ nanorods, the rGO/MnO₂ nano-heterostructure exhibits impressive field emission (FE) performance in the terms of the low turn-on field of 1.4 V/µm for an emission current density of 10 µA/cm² and high current density of 600 µA/cm² at relatively very low applied electric field of 3.1 V/µm.  The isolated MnO₂ nanorods display a high turn-on field of 7.1 for emission current density of 10 µA/cm² and low current density 221 µA/cm² at an applied field of 8.1 V/µm. Besides the superior FE characteristics of the rGO/MnO₂ nano-heterostructure, the emission current remains quite stable over the continuous 2h period of measurement. The improvement of the FE characteristics of the rGO/MnO₂ heterostructure can be ascribed to the nanometric features and the lower work function (6.01 and 6.12 eV for the rGO with 8% and 16% oxygen contents) compared to the isolated α-MnO₂(100) surface (Φ =7.22 eV) as predicted from complementary first-principles electronic structure calculations based on density functional theory (DFT) methods.  These results suggest that an appropriate coupling of rGO with MnO₂ nanorods would have a synergistic effect of lowering the electronic work function, resulting in a beneficial tuning of the FE characteristics.

The experimental and Density functional theory (DFT) theoretical simulation datasets are available in the .xlsx format (can be viewed either by MS Office or Libre Office) comprising 6 datasheets named by their contents. The experimental data comprises of X-ray diffraction, Field Emission (FE), and XPS data of MnO2 and rGO/MnO2 heterostructure. Data for the DFT optimized structures for the bulk MnO2, rGO with 8 and 16 % oxygen contents, and the rGO/MnO2 heterostructures available in the CONTCAR format of the VASP simulation program. The CONTCAR files consist of lattice parameter and atomic positions and can be viewed either by MS Office or WordPad. The electrostatic potential data for the rGO with 8 and 16 % oxygen contents and the rGO/MnO2 heterostructures are provided. All data can be plotted using any plotting software, e.g., xmgrace, excel. 

Research results based upon these data are published at https://doi.org/10.1039/D0RA03360J