The sp²-sp³ Carbon Hybridization Content of Nanocrystalline Graphite from Pyrolyzed Vegetable Oil, Comparison of Electrochemistry and Physical Properties with Other Carbon Forms and Allotropes

Authors

David Estrada, Boise State UniversityFollow
Paul H. Davis, Boise State UniversityFollow
Twinkle Pandhi, Boise State University
Katie Yocham, Boise State University
Kari Higginbotham, Boise State University

Document Type

Article

Publication Date

4-2019

Abstract

Nanocrystalline (nc) graphite produced from pyrolyzed vegetable oil has properties that deviate from typical graphites, but is similar to the previously reported Graphite from the University of Idaho Thermolyzed Asphalt Reaction (GUITAR). These properties include (i) fast heterogeneous electron transfer (HET) at its basal plane and (ii) corrosion resistance beyond graphitic materials. To discover the structural basis for these properties, characterization of this nc-graphite was investigated with Raman and X-ray photoelectron spectroscopies, nano-indentation, density, X-ray diffraction (XRD), thermogravimetric and elemental analyses. The results indicate that this nc-graphite is in Stage-2 of Ferrari’s amorphization trajectory between amorphous carbon (a-C) and graphite with a sp²/sp³ carbon ratio of 85/15. The nano-crystallites size of 1.5 nm from XRD is consistent with fast HET rates as this increases the density of electronic states at the Fermi-level. However, d-spacing from XRD is 0.350 nm vs. 0.335 for graphite. This wider distance does not explain its corrosion resistance. Literature trends suggest that increasing sp² content in a-C’s increase both HET and corrosion rates. While nc-graphite’s HET rate follows this trend, it exhibits higher than predicted corrosion resistance. In general, this form of nc-graphite matches the best examples of boron-doped diamond in HET and corrosion rates.

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Copyright Statement

This is an author-produced, peer-reviewed version of this article. © 2019, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-No Derivatives 4.0 license. The final, definitive version of this document can be found online at Carbon, doi: 10.1016/j.carbon.2018.12.058

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.

Publication Information

Estrada, David; Davis, Paul H.; Pandhi, Twinkle; Yocham, Katie; and Higginbotham, Kari. (2019). "The sp2-sp3 Carbon Hybridization Content of Nanocrystalline Graphite from Pyrolyzed Vegetable Oil, Comparison of Electrochemistry and Physical Properties with Other Carbon Forms and Allotropes". Carbon, 144, 831-840. https://doi.org/10.1016/j.carbon.2018.12.058