X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms

Abstract

SummaryX-ray photoelectron spectroscopy (XPS) is one of the best tools for studying the chemical modification of surfaces, and in particular the distribution and bonding of heteroatom dopants in carbon nanomaterials such as graphene and carbon nanotubes. Although these materials have superb intrinsic properties, these often need to be modified in a controlled way for specific applications. Towards this aim, the most studied dopants are neighbors to carbon in the periodic table, nitrogen and boron, with phosphorus starting to emerge as an interesting new alternative. Hundreds of studies have used XPS for analyzing the concentration and bonding of dopants in various materials. Although the majority of works has concentrated on nitrogen, important work is still ongoing to identify its precise atomic bonding configurations. In general, care should be taken in the preparation of a suitable sample, consideration of the intrinsic photoemission response of the material in question, and the appropriate spectral analysis. If this is not the case, incorrect conclusions can easily be drawn, especially in the assignment of measured binding energies into specific atomic configurations. Starting from the characteristics of pristine materials, this review provides a practical guide for interpreting X-ray photoelectron spectra of doped graphitic carbon nanomaterials, and a reference for their binding energies that are vital for compositional analysis via XPS.

Defect Engineered 2D Materials for Energy Applications

“…Similarly, pyrrolic configuration gives rise to peaks in the range 399.8-401.2 eV, while the peak around 400.5 eV (blue colored) is associated with the graphitic configuration. The orange-colored peak at ~401.5 and 406 eV may be attributed to different nitrogenated adsorbents [20,21]. XPS results confirmed that the atomic percentages of nitrogen in S1, S2, and S3 were 0.2, 2.5, and 3.8 %, respectively [7].…”

“…As shown in Figure 3a, we identified XPS peaks corresponding to graphitic, pyrrolic, and pyridinic configurations [21]. For pyridinic configuration, the N1s peak positions reported in the literature are usually in the range 398.1-399.3 eV.…”

Controlling pyridinic, pyrrolic, graphitic, and molecular nitrogen in multi-wall carbon nanotubes using precursors with different N/C ratios in aerosol assisted chemical vapor deposition

“…[14][15][16][17] The most common forms of embedded nitrogen discussed in the literature are graphitic, pyridinic and pyrrolic nitrogen. 1,[18][19][20] Graphitic nitrogen refers to a nitrogen atom with three carbon neighbours in a hexagonal lattice, if the nitrogen is two-fold coordinated similar to that is found in pyridine, it is called pyridinic, and three-fold coordinated nitrogen in a region of defective non-aromatic lattice is associated with pyrrolic nitrogen. While the majority of reports argue that, due to their different stabilities, the concentration of these different types of nitrogen atoms in N-MWCNTs is largely controlled by the synthesis temperature 21,22 some accounts also consider the nature of the precursor to be a crucial factor.…”

Impact on CO2 Uptake of MWCNT after Acid Treatment Study

“…In case of C 1s signal the following functional groups were identified [35][36][37]: graphite (sp 2 C) 284.6 ± 0.3 eV, carbon in defects (sp FWHM (full width at half maximum) was set at the same value for each component, due to the same transition, except satellite. In case of O 1s signal the following functional groups were identified [35,38]: NO 2 , C=O 531.1 ± 0.3 eV, C-O 532.8 ± 0.5 eV, and COOH 534.2 ± 0.3 eV.…”