Investigation on the use of graphene oxide as novel surfactant to stabilize weakly charged graphene nanoplatelets

Abstract

This paper presents a unique synergistic behavior between a graphene oxide (GO) and graphene nanoplatelet (GnP) composite in an aqueous medium. The results showed that GO stabilized GnP colloid near its isoelectric point and prevented rapid agglomeration and sedimentation. It was considered that a rarely encountered charge-dependent electrostatic interaction between the highly charged GO and weakly charged GnP particles kept GnP suspended at its rapid coagulation and phase separation pH. Sedimentation and transmission electron microscope (TEM) micrograph images revealed the evidence of highly stable colloidal mixtures while zeta potential measurement provided semi-quantitative explanation on the mechanism of stabilization. GnP suspension was confirmed via UV-vis spectral data while contact angle measurement elucidated the close resemblance to an aqueous solution indicating the ability of GO to mediate the flocculation prone GnP colloids. About a tenfold increase in viscosity was recorded at a low shear rate in comparison to an individual GO solution due to a strong interaction manifested between participating colloids. An optimum level of mixing ratio between the two constituents was also obtained. These new findings related to an interaction between charge-based graphitic carbon materials would open new avenues for further exploration on the enhancement of both GO and GnP functionalities particularly in mechanical and electrical domains.

Facile Synthesis of MnPO4·H2O Nanowire/Graphene Oxide Composite Material and Its Application as Electrode Material for High Performance Supercapacitors

“…As we know, there are some oxide functional groups on the surface of GO that can enhance its hydrophilicity. Therefore, GO may act as the surfactant in this system, which may lead to the formation of this homogeneous morphology [27][28][29]. In addition, GO, in this system, not only acts as a surfactant but also serves as a conductive agent in the sample, which contributes to the highly improved stability and great anti-aggregation ability during the charge-discharge process.…”

Oxygen Electroreduction on Pt Nanoparticles Deposited on Reduced Graphene Oxide and N‐doped Reduced Graphene Oxide Prepared by Plasma‐assisted Synthesis in Aqueous Solution

“…[21,36] High resolution XPS spectra of Pt/rGOÀN and Pt/rGO catalysts in the Pt4 f and C1s regions are presented in Figure S4 and discussed in Supporting information. [37,38] Therefore, we may consider that the prepared rGO flakes were also negatively charged and they were repelled from PtNPs in solution at pH 7.6. As can be seen from Figure 3a, in Pt/rGO catalyst, prepared with NaOH additives (synthesis conditions are specified in Figure 1 for curve 2) rGO flakes were not successfully covered by small nonagglomerated PtNPs.…”

Heat Transfer Capability of (Ethylene Glycol + Water)-Based Nanofluids Containing Graphene Nanoplatelets: Design and Thermophysical Profile

“…This superior contact could lead to a reduction of Kapitza resistance at the graphene-fluid interface and, consequently, help to improve the effective thermal conductivity of the nanofluid [15]. Another upside of graphene nanomaterials is the relatively easy and cost-effective production at a large scale [13, 16, 17]. Hence, graphene appears to meet all the conditions to develop new nanofluids with improved thermal properties.…”