Graphene Oxide-Assisted Dispersion of Pristine Multiwalled Carbon Nanotubes in Aqueous Media

Abstract

Graphene oxide (GO) sheets, considered as “soft” two-dimensional macromolecules containing multiple aromatic regions and hydrophilic oxygen groups, can adsorb the pristine multiwalled carbon nanotubes (MWNTs) through the π-stacking interaction, thus causing pristine MWNTs to stably disperse and fractionate in aqueous media. The water-soluble and insoluble complexes can be obtained by changing the initial proportion of MWNTs to GO sheets, which are important for noncovalent approaches toward solubilizing CNTs and open a new way for GO applications in colloidal chemistry. Solubility results indicate that the GO sheets are prone to stabilize MWNTs with larger diameters. When the diameters of CNTs decrease to a critical value, the π-stacking interactions are weakened by large surface energy among CNTs themselves; the CNTs are inclined to form bundles or twisted structures instead of CNT−GO complexes. This can be probably developed into a practical method to fractionate MWNTs with different outer diameters in water.

Facile synthesis of reduced graphene oxide/MWNTs nanocomposite supercapacitor materials tested as electrophoretically deposited films on glassy carbon electrodes

“…This is most likely due to the increase in MWNTs overcoming the stabilizing effect of the GO. The UV-vis spectrum of a GO solution ( Figure 1) shows a peak centred at a maximum wavelength of 227 nm, indicating π -π transitions of aromatic C-C bonds while a shoulder peak at 300 nm can be assigned to n -π transitions of C=O bonds ( Figure 1a) that correspond to previously published results [5,9,13].…”

“…This dispersion was purified as per the method reported by Zhang [13] as follows. The dispersion was centrifuged for 30 min at 8000 rpm to remove the unstabilized MWNTs, followed by centrifugation at 14000 rpm for 20 min to separate the GO/MWNTs from excess GO.…”

“…Tian reported that graphene oxide can be used as a dispersing agent for single-walled carbon nanotubes (SWNTs) [12] whilst Zhang used graphene oxide to assist in the aqueous dispersion of multiwalled carbon nanotubes (MWNTs) [13]. Others have prepared hybrid graphene/carbon nanotube structures using hydrazine; a highly toxic chemical and a strong reducing agent [14].…”

Carbon Nanomaterials for Flexible Energy Storage

“…Furthermore, previous studies have established that graphene oxide could work as an efficient surfactant to disperse CNTs and therefore uniform mixture of CNTs and graphene could be prepared. [63] When prepared as flexible electrodes, such composites generally have better performance than either of CNTs or graphene alone, and a remarkable specific capacitance of 265 F/g was achieved for electrodes with 16 wt% of multiwalled carbon nanotubes (Figure 4). [37] In another similar study, 326 F/g was obtained for composite electrodes with 10% CNTs, which is also substantially higher than pure CNTs and graphene electrodes.…”

Synthesis of functionalized CNTs/hyperbranched polyester nanocomposites

“…Therefore, the aggregation problem of GO and CNTs has to be resolved in order to move the field forward. In recent years, it was found that the dispersion of CNTs/GO hybrid in solution media can be improved by ultrasonication [3,4]. Moreover, the chemical functionalization was proved to provide better long-term stability and better dispersibility [5].…”