Chemical Modification of Graphene Oxide by Nitrogenation: An X-ray Absorption and Emission Spectroscopy Study
Nitrogen-doped graphene oxides (GO:N x) were synthesized by a partial reduction of graphene oxide (GO) using urea [CO(NH 2) 2 ]. Their electronic/bonding structures were investigated using X-ray absorption near-edge structure (XANES), valence-band photoemission spectroscopy (VB-PES), X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS). During GO:N x synthesis, different nitrogen-bonding species, such as pyrrolic/graphitic-nitrogen, were formed by replacing of oxygen-containing functional groups. At lower N-content (2.7 at%), pyrrolic-N, owing to surface and subsurface diffusion of C, N and NH is deduced from various X-ray spectroscopies. In contrast, at higher N-content (5.0 at%) graphitic nitrogen was formed in which each N-atom trigonally bonds to three distinct sp 2 -hybridized carbons with substitution of the N-atoms for C atoms in the graphite layer. Upon nitrogen substitution, the total density of state close to Fermi level is increased to raise the valence-band maximum, as revealed by VB-PES spectra, indicating an electron donation from nitrogen, molecular bonding C/N/O coordination or/and lattice structure reorganization in GO:N x . The well-ordered chemical environments induced by nitrogen dopant are revealed by XANES and RIXS measurements.
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- Tamkang Univ., Taipei (Taiwan). Dept. of Physics
- Univ. of South Afric, Johannesburg (South Africa). Dept. of Physics
- Ulster Univ., Newtownabbey (United Kingdom). Engineering Research Inst.
- National Univ. of Kaohsiung (Taiwan). Dept. of Applied Physics
- National Synchrotron Radiation Research Center, Hsinchu (Taiwan)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source; Univ. of California, Santa Cruz, CA (United States). Dept. of Chemistry and Biochemistry
- Publication Date:
- Grant/Contract Number:
- AC02-05CH11231
- Type:
- Accepted Manuscript
- Journal Name:
- Scientific Reports
- Additional Journal Information:
- Journal Volume: 7; Journal ID: ISSN 2045-2322
- Publisher:
- Nature Publishing Group
- Research Org:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Org:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; electronic properties and devices
- OSTI Identifier:
- 1379732