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N-rGO paper_v9_JPCLett_final_figuremod.pdf (918.52 kB)

Characterizing Nitrogen Sites in Nitrogen-Doped Reduced Graphene Oxide: A Combined Solid-State 15N NMR, XPS and DFT Approach

preprint
submitted on 14.01.2021, 01:39 and posted on 18.01.2021, 06:22 by Gunwoo Kim, Jeongjae Lee, Tao Liu, Clare P. Grey

Despite the potential applications in energy storage and conversion systems such as Li-oxygen batteries and fuel cells, the nature and distribution of doped nitrogen sites in reduced graphene oxides are still not well understood. In this work, we report a combined approach of 15N solid-state nuclear magnetic resonance (NMR) spectroscopy alongside the predominantly used X-ray photoelectron spectroscopy (XPS) to characterize the nitrogen environments in reduced graphene oxides. Application of 1H-15N low-power double quantum cross polarization under fast magic angle spinning with Carr-Purcell-Meiboom-Gill scheme shows selective detection of protonated sites with low-power radiofrequency irradiation. NMR shift calculations of a series of N-containing molecules and a graphene nanoflake model were performed to help interpret the experimental data. This work demonstrates a powerful approach to identify and quantify the different nitrogen environments in doped graphene materials and can also be widely applied to similar graphitic carbon-based materials with other dopants.

Funding

EUHorizon 2020 GrapheneCore1-No.696656

Darwin College

DE-SC0012704

History

Email Address of Submitting Author

jsquared635@gmail.com

Institution

University of Cambridge

Country

United Kingdom

ORCID For Submitting Author

0000-0003-4294-4993

Declaration of Conflict of Interest

N/A

Exports

ChemRxiv

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