Cross‐sectional structural characterization of the surface of exfoliated HOPG using HRTEM‐EELS

Abstract

We analyzed the surface atomic structure of highly oriented pyrolytic graphite (HOPG) substrate exfoliated with adhesive tape, using high-resolution transmission electron microscopy and scanning transmission electron microscopy-electron energyloss spectroscopy (STEM-EELS). The surface step height of the exfoliated HOPG substrate was determined using high-angle annular dark-field-scanning transmission electron microscopy (HAADF-STEM) images and the depth profiles of the EELS spectra of a cross-sectioned thin foil specimen prepared via focused ion beam milling. The exfoliated surface of the HOPG substrate presented disordered and curved graphene layers. The STEM-EELS measurements indicated that upon exfoliation, the surface of the HOPG substrate reacted with atmospheric water and oxygen molecules.

Surface atomic structures of nickel plating films reacted with methane at high temperature

“…Hence, the increase in the π + σ plasmon energy indicates that carbon atoms with sp 3 bonds are more abundant near the Ni plating film surface. On the other hand, the increase in the FWHM value of the π * peak indicates a decrease in the number of π bonds toward the Ni plating film surface, 19,20 which is consistent with the aforementioned increase in the sp 3 bonds toward the Ni plating film surface.…”

“…The EELS spectra of the deposited carbon were obtained from the slabs numbered 1–21 and are displayed in Figure 12 for the (a) low‐ and (b) high‐loss spectra. Each EELS spectrum displays the summation of all EELS signals counted for the corresponding slabs 19,20 …”

High-corrosion-resistance mechanism of graphitized platelet-type carbon nanofibers in the OER in a concentrated alkaline electrolyte

“…This region is assigned to the C–OH bonds of hydroxyl groups (Table S2†). 70–74 Therefore, the EELS results revealed the introduction of hydroxyl groups on the edge plane surface after anodic polarization at 1.8 V vs. RHE. As mentioned above, the ILSEM and TEM observations demonstrate that the carbon corrosion on the carbon edge plane is negligibly slow compared with that on the carbon basal plane.…”

“…All spectra show a peak at 285.5 eV, corresponding to the π* electronic transition of sp 2 type carbon. 70–74 Only the edge surface spectra of TB and pCNF2400 showed a shoulder in a higher-energy region of 286 eV. This region is assigned to the C–OH bonds of hydroxyl groups (Table S2†).…”

“…In the low-loss region of the carbon materials, a broad peak appears between 10 and 40 eV and is identied as a combination of p and s electronic excitations. [69][70][71][72] The spectra of the bulk region for TB and pCNF2400 show a p + s peak at 26 eV, which is assigned to graphite. In addition, each carbon surface showed an additional p + s broad peak at approximately 16 eV.…”