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Published March 2018 | public
Conference Paper

High yield bottom-up PECVD synthesis of graphene nanoribbons and their application in supercapacitors

Abstract

Increasing global energy demands and climate change concerns related to energy use require developing enduring and efficient energy technologies. Supercapacitors could significantly contribute to energy technol. in this respect due to their long cycle life and rapid charge/discharge capabilities. However, supercapacitors suffer from poor energy d. which severely limits their application. Because supercapacitors store energy capacitively at electrode surfaces, one obvious strategy to improve energy d. is to use high surface area and high capacitance electrode materials. Graphene nanoribbons, long and narrow strips of graphene, are a promising supercapacitor electrode material due to (i) good elec. cond., (ii) high surface area as a two-dimensional material, and (iii) abundant edges which have enhanced capacitance compared to the graphene basal plane. Current graphene nanoribbon fabrication procedures are either unscalable or incorporate polymer and/or metal contaminants, but we have developed a high yield bottom-up PECVD synthesis of high quality graphene nanoribbons. Deposition takes place at ca. 500 mTorr in a 0.5 in. (outer diam.) quartz tube on copper foil in a hydrogen/methane plasma with 1,2-dichlorobenzene precursor. Graphene nanoribbon growth begins as benzene radicals seed onto copper foil, and arom./methane carbon species propagate growth. Characterization confirms the synthesis of graphene nanoribbons. Raman spectroscopy measurements show G and 2D peaks corresponding to graphene structure and a strong D peak corresponding to graphene edge states. UPS measurements reveal a work function of 4.45 eV compared to 4.5 eV for pristine graphene. EDS and SAD measurements in a TEM confirm at. purity and a hexagonal lattice consistent with graphene. Finally, SEM images demonstrate high aspect ratios with widths less than 500 nm and lengths greater than 5 μm. Although these graphene nanoribbons are too wide for many applications, this represents a starting point for developing a very large scale integrable synthesis of graphene nanoribbons as we are able to produce graphene nanoribbons at a rate of 0.05 mg/cm2/min. Graphene nanoribbons have been characterized for supercapacitor application and demonstrate excellent power and energy densities.

Additional Information

© 2018 American Chemical Society.

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023