Chemical Modification of Graphene Oxide by Nitrogenation: An X-ray Absorption and EmissionSpectroscopy Study

CH Chuang, SC Ray, D Mazumder, S Sharma, A Ganguly, Pagona Papakonstantinou, JW Chiou, HM Tsai, HW Shiu, CH Chen, HJ Lin, J Guo, WF Pong

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Abstract

Nitrogen-doped graphene oxides (GO:Nx) were synthesized by a partial reduction of graphene oxide (GO) using urea [CO(NH2)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:Nx 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 sp2-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:Nx. The well-ordered chemical environments induced by nitrogen dopant are revealed by XANES and RIXS measurements.
Original languageEnglish
Pages (from-to)42235
JournalScientific Reports
Volume7
DOIs
Publication statusPublished - 10 Feb 2017

Keywords

  • nitrogen doped reduced graphene oxide
  • X-ray Absorption spectroscopy (XANES)
  • X ray emission spectroscopy
  • valence-band photoemission spectroscopy (VB-PES)
  • resonant inelastic X-ray scattering (RIXS).

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    Chuang, CH., Ray, SC., Mazumder, D., Sharma, S., Ganguly, A., Papakonstantinou, P., Chiou, JW., Tsai, HM., Shiu, HW., Chen, CH., Lin, HJ., Guo, J., & Pong, WF. (2017). Chemical Modification of Graphene Oxide by Nitrogenation: An X-ray Absorption and EmissionSpectroscopy Study. Scientific Reports, 7, 42235. https://doi.org/10.1038/srep42235