NMR-based structural modeling of graphite oxide using multidimensional 13C solid-state NMR and ab initio chemical...

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Chemically modified graphenes and graphite materials are of interest for electronics and structural applications.
• Accurate structural modeling of noncrystalline graphite-based materials using spectroscopic data is challenging.

Purpose of the Study:

• To develop and present a solid-state NMR (SSNMR)-based approach for constructing structural models of graphite oxide (GO).
• To validate structural models for GO, a key modified graphene precursor.

Main Methods:

• Utilized 2D (13)C double-quantum/single-quantum correlation SSNMR spectroscopy on (13)C-labeled GO.
• Compared experimental spectra with simulations based on ab initio geometry optimization and chemical shift calculations for various structural models.
• Employed 2D (13)C chemical shift anisotropy (CSA)/isotropic shift correlation SSNMR to analyze CSA patterns.

Main Results:

• The experimental SSNMR spectra of GO were best reproduced by a geometry-optimized model based on the Lerf-Klinowski model.
• This validated model comprises interconnected sp(2), 1,2-epoxide, and COH carbons.
• Previously proposed models, including those with 1,3-epoxide carbons, were excluded.
• Calculated chemical shift tensors accurately reproduced the measured (13)C CSA patterns.

Conclusions:

• The presented SSNMR-based approach effectively models the structure of graphite oxide.
• The Lerf-Klinowski model, with its specific carbon arrangements, is strongly supported for GO.
• This methodology is adaptable for structural analysis of other modified graphenes and graphite-based systems.