Stepwise Reduction of Graphene Oxide (GO) and Its Effects on Chemical and Colloidal Properties

Abstract

Graphene Oxides (GO) typically contains different oxygen containing groups such as hydroxyl, carboxyl and epoxy, and reduced GO (r-GO) represents a family of material with diverse chemical properties. In an effort to understand how properties of r-GO change as GO is reduced, a stepwise reduction of the same GO to r-GO containing different levels of oxygen was carried out, and their corresponding chemical and colloidal properties are reported. Starting with GO containing 49 percent oxygen, r-GOs containing 31, 19 and 9 percent oxygen were synthesized. The aqueous behavior in terms of solubility gradually decreased from 7.4 µg/ml for GO to nearly zero for r-GO with 9% oxygen, while dispersibility under sonication decreased from 8 to 2.5 µg/ml for the same samples. Hydrophobicity index as measured as the octanol water partition coefficient decreased from −3.89 to 5.2% as oxygen content dropped from 49 to 9%. Colloidal behavior was also dramatically affected by reduction, and critical coagulation concentration (CCC) dropped from 28 to 15 in presence of 0.5 mmole/l NaCl and from 6 to 2 in presence of 0.5 mmole/l MgCl2 as the oxygen in the original GO was reduced to 9%.

Development of a Sensitive Self-Powered Glucose Biosensor Based on an Enzymatic Biofuel Cell

“…The electrochemical reduction of GO through cyclic voltammetry was chosen to control the extent of reduction of the GO. We measured the IR absorption spectra of the starting GO and the resulting rGO ( Figure S1 ), which confirmed that the number of oxygen-containing functional groups, such as C–O (1060 cm −1 ), C–OH (1226 cm −1 ), and C=O (1733 cm −1 ) [ 39 ], decreased as the GO is electrochemically reduced. Moreover, we checked the electrode active surface area of the GO- and rGO-modified electrode using a standard solution of 5 mM Fe(CN) 6 3+ containing 0.1 M KCl.…”

Blood Pressure Sensors: Materials, Fabrication Methods, Performance Evaluations and Future Perspectives

“…rGO, on the other hand, is prepared from rGO by thermal, chemical, or electrical treatments. Hence there are always some defects resulting from unreduced O 2 functional groups in or on the rGO surface, and subsequently, rGO cannot have the perfect graphene structure, which was described above [267].…”

Strategies for the Development of Metallic‐Nanoparticle‐Based Label‐Free Biosensors and Their Biomedical Applications

“…They used nanosized graphene oxide (NGO) to cover AgNPs (Ag@NGO). Two‐dimensional NGO is inert, which saves NPs from oxidation and allows light to pass easily . These properties of NGO make it suitable for use as a protective layer on AgNPs as a SERS substrate.…”

“…[126] They used nanosized graphene oxide (NGO) to cover AgNPs (Ag@NGO).T wo-dimensional NGO is inert, which saves NPs from oxidationa nd allows light to pass easily. [127] These properties of NGO make it suitable for use as ap rotective layer on AgNPs as aS ERS substrate. The Raman spectra of NGO and Ag@NGO showedt hat the Da nd Gb ands of NGO were intensified after attachment of AgNPs; this is ascribed to the sharp SPR of AgNP.T he Raman spectra of HepG-2 cancer cells without the Ag@NGO substrate displayed no band duet o the low scattering intensity of cell components.…”