Synthesis of Highly n‐Type Graphene by Using an Ionic Liquid

Near-edge x-ray absorption fine structure spectroscopy study of nitrogen incorporation in chemically reduced graphene oxide

“…The pyrazole/pyrazoline standards show a prominent peak attributed to aromatic C-C bonding at a binding energy of approximately 284.0 eV along with a C ¼ N feature at a binding energy of $285.2 eV. 23,26,39,41 Additional features are also observed at $286.4 and $287.8 eV, which can be ascribed to C-NR 2 and C ¼ O bonds, respectively, based on literature precedent and XPS measurements of standards. 42 Thermal annealing at 150 C does not substantially alter the XPS spectrum of GO.…”

“…Given the appreciable nitrogen concentrations in these samples, the distinct feature that emerges at $285.1-285.6 eV is assigned to C ¼ N bonds. 23,26,39,41 As a result of the relatively lower electronegativity of nitrogen as compared to oxygen, this feature appears at lower energy as compared to the C-O and C ¼ O peaks (which further diminish local charge density on the carbon atoms). The higher energy peaks at $286.3-287.1 eV and $287.9-288.5 eV are attributed to C-O and C ¼ O bonds in remnant functional groups, respectively.…”

“…1, two distinct peaks are observed in the C 1s spectrum of GO at $284.4 and $286.5 eV, which can be attributed to aromatic C-C bonds and C-O functional groups on the GO sheets, respectively; an asymmetric third component can also be deconvoluted at approximately 288.1 eV, corresponding to C ¼ O bonding. 23,26,[39][40][41] The strong splitting of the C 1s feature is characteristic of GO and indicates the substantial disruption of the p-conjugated framework induced by oxidative functionalization. 23,26,[39][40][41] The Lerf-Klinowski model has C-O-C epoxide and C-OH hydroxyl groups extensively perturbing the sp 2 hybridization of the graphene basal planes, and the abundance of these functionalities in GO is evidenced by the strong intensity of the C-O feature.…”

“…12,13,[23][24][25][26] The introduction of NH 3 gas during the growth of graphene on metal foils has allowed different nitrogen doping motifs to be established including isolated substitutional doping of graphene confined to a singular sublattice as well as incorporation of N-N fragments that are located meta to each other (on 1,3 sites) within the six-membered aromatic rings. 14,24 The chemical identity and configuration of nitrogen dopants within the graphene lattice remains widely contested but evidence for pyridinic, quaternary, pyrrolic, and aminic nitrogen species has been presented based on x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning tunneling microscopy, x-ray absorption spectroscopy, scanning electron microscopy, and transmission electron microscopy.…”

Sustainable process for all-carbon electrodes: Horticultural doping of natural-resource-derived nano-carbons for high-performance supercapacitors

“…In particular, the nitrogen-and oxygen-groups attached on the graphitic walls of VGNS can act as the donor/acceptor sites which affect the charge distribution and shift the Fermi level of carbon atoms in the graphitic plane, leading to more electrochemically active surface with higher electron conductivity [7,10,43]. Specifically, the presence of additional lone pair electron in the N functional groups is capable of delocalising the electron distribution of doped sample and shifting the Fermi level up to make n-type semiconductor [45]; while O functional groups such as -OH, -COOH, and -CO will bring the Fermi level down to make p-type semiconductors [54]. Therefore, sites with different functional groups may create different charge carriers and which carrier dominates will depend on the ratio of N or O functional groups on the surface.…”