Three-dimensional arrays of graphenated carbon nanotubes
- PDF / 369,796 Bytes
- 8 Pages / 584.957 x 782.986 pts Page_size
- 38 Downloads / 162 Views
Brian R. Stoner RTI International, Center for Materials and Electronic Technologies, Durham, North Carolina 27709
Jeffrey T. Glass Department of Electrical and Computer Engineering, Pratt School of Engineering, Duke University, Durham, North Carolina 27708 (Received 14 October 2011; accepted 18 January 2012)
Graphene and carbon nanotubes (CNTs) are fascinating materials, both scientifically and technologically, due to their exceptional properties and potential use in applications ranging from high-frequency electronics to energy storage devices. This manuscript introduces a hybrid structure consisting of graphitic foliates grown along the length of aligned multiwalled CNTs. The foliate density and layer thickness vary as a function of deposition conditions, and a model is proposed for their nucleation and growth. The hybrid structures were studied using electron microscopy and Raman spectroscopy. The foliates consist of edges that approach the dimensions of graphene and provide enhanced charge storage capacity. Electrochemical impedance spectroscopy indicated that the weight-specific capacitance for the graphenated CNTs was 5.4 that of similar CNTs without the graphitic foliates. Pulsed charge injection measurements demonstrated a 7.3 increase in capacitance per unit area. These data suggest that this unique structure integrates the high surface charge density of the graphene edges with the high longitudinal conductivity of the CNTs and may have significant impact in charge storage and related applications.
I. INTRODUCTION
Due to its unique structures and properties, carbon has generated excitement among materials scientists and engineers for many decades, from the synthesis of diamond1,2 to Buckminster fullerenes3 and carbon nanotubes (CNTs).4 Recently, graphene has been added to this list due to very unusual properties such as charge mobility, band structure, and mechanical strength. This was emphasized by the Nobel Prize in Physics in 2010 “for groundbreaking experiments regarding the two-dimensional material graphene” awarded to Andre Geim and Konstantin Novoselov.5,6 Numerous articles have been published on the synthesis and properties of graphene (for three recent reviews see Refs. 7–9). There have also been earlier reports on graphitic platelets deposited after CNT deposition in a twostep process.10,11 The present authors recently reported on the enhanced electrochemical double-layer performance of graphenated CNTs with varying foliate density, demonstrating the potential application of this hybrid structure.12 Furthermore, recent reviews7–9 have also described vertically a)
Address all correspondence to this author. e-mail: [email protected] b) Present address: Luna Innovations Incorporated, 521 Bridge Street, Danville, Virginia 24541 DOI: 10.1557/jmr.2012.43 1046
J. Mater. Res., Vol. 27, No. 7, Apr 14, 2012
http://journals.cambridge.org
Downloaded: 16 Jul 2014
oriented graphene nanosheet structures but have not discussed the integration of graphene or graphitic nanosheets with CNTs. The funda
Data Loading...
