Fabrication and morphology tuning of graphene oxide nanoscrolls.

Carlo A Amadei,Gregory J Silverberg,Itai Y Stein,Chad D Vecitis,Brian L Wardle

doi:10.1039/c5nr07983g

Carlo A Amadei, Gregory J Silverberg + Show 3 more

Open Access

https://doi.org/10.1039/c5nr07983g

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Abstract

Here we report the synthesis of graphene oxide nanoscrolls (GONS) with tunable dimensions via low and high frequency ultrasound solution processing techniques. GONS can be visualized as a graphene oxide (GO) sheet rolled into a spiral-wound structure and represent an alternative to traditional carbon nano-morphologies. The scrolling process is initiated by the ultrasound treatment which provides the scrolling activation energy for the formation of GONS. The GO and GONS dimensions are observed to be a function of ultrasound frequency, power density, and irradiation time. Ultrasonication increases GO and GONS C-C bonding likely due to in situ thermal reduction at the cavitating bubble-water interface. The GO area and GONS length are governed by two mechanisms; rapid oxygen defect site cleavage and slow cavitation mediated scission. Structural characterization indicates that GONS with tube and cone geometries can be formed with both narrow and wide dimensions in an industrial-scale time window. This work paves the way for GONS implementation for a variety of applications such as adsorptive and capacitive processes.

Highlights

Previously synthesized graphene oxide (GO) nano-scroll (GONS) cannot be characterized by metrics such as dimension since the structures are typically composed of crumpled and/or folded GO42,46 instead of a properly scrolled morphology
The synthesis of graphene oxide nanoscrolls with tunable dimensions was achieved via 20 kHz low frequency and 390 kHz high frequency ultrasonic solution processing techniques
Simultaneous fine-tuning of GO and GONS dimensions and surface chemistry was achieved in an industrial-scale time window

Summary

Introduction

Recent work on graphene oxide (GO) indicates there is potential for nano-manufacturing via cost-effective solution techniques[4,5,6,7,8] that retain GO properties[9,10,11] such as thermal conductivity,[12] mechanical stiffness,[13] elasticity,[14] and optical transparency.[15] the GO oxygen functional groups act as both a spacer,[9,16,17,18,19] and a functionalized site for molecular adsorption,[20,21] which enables GO conversion into nanomorphologies that could be used for applications such as filtration membranes,[17] supercapacitors,[22] electrochemical sensors,[23] and hydrogen storage devices.[24] One potential nano-morphology is a GO nano-scroll (GONS) i.e., a GO sheet rolled into a spiral-wound structure (Fig. 1a). GONS are similar in morphology to a carbon nanotube (CNT), but with a significantly more accessible inter-wall area

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