Fabrication and Characteristics of Reduced Graphene Oxide Produced with Different Green Reductants

Abstract

There has been an upsurge of green reductants for the preparation of graphene materials taking consideration of human health and the environment in recent years. In this paper, reduced graphene oxides (RGOs) were prepared by chemical reduction of graphene oxide (GO) with three green reductants, L-ascorbic acid (L-AA), D-glucose (D-GLC) and tea polyphenol (TP), and comparatively characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectra, Raman spectra and electrical conductivity analysis. Results showed that all these three reductants were effective to remove oxygen-containing functional groups in GO and restore the electrical conductivity of the obtained RGO. The RGO sample with L-ascorbic acid as a reductant and reduced with the existence of ammonia had the highest electrical conductivity (9.8 S·cm-1) among all the obtained RGO samples. The mechanisms regarding to the reduction of GO and the dispersion of RGO in water were also proposed. It is the good dispersibility of reduced graphene oxide in water that will facilitate its further use in composite materials and conductive ink.

Preparation and characterization of graphene oxide based membranes as possible Gas Diffusion Layers for PEM fuel cells with enhanced surface homogeneity

“…In particular: at 3419 cm -1 stretching of hydroxyl groups is present; at 1730 cm -1 it is possible to find stretching vibration of carboxyl groups; stretching of sp 2 carbon and bending of hydroxyl groups of water are both responsible of the peak at 1623 cm -1 ; at 1396 cm -1 there is the bonding vibration of hydroxyl bond; at 1235 cm -1 and 1064 cm -1 it is possible to find the stretching of epoxy group and of carboxyl group, respectively. All these peaks are aligned with other literature studies [12,23,24]. Reporting in the same graph only r-GO 24h, r-GO 48h, r-GO 96h spectrum, compared to GO spectra, it is possible to clearly define how the intensity of the peaks decreases as the time of reduction increases [18,24] (Fig.…”

“…All these peaks are aligned with other literature studies [12,23,24]. Reporting in the same graph only r-GO 24h, r-GO 48h, r-GO 96h spectrum, compared to GO spectra, it is possible to clearly define how the intensity of the peaks decreases as the time of reduction increases [18,24] (Fig. 8 on the left).…”

“…3. Membranes named r-GO XXh were obtained, where XX represents the reduction time in hours (12,24,36,48,72,96). Moreover, a membrane was obtained by the same procedure with a diluted GO, without any reduction; it represents the blank test solution and it is named GO Membrane [ Fig.…”

One-Pot Green Synthesis of Highly Reduced Graphene Oxide Decorated with Silver Nanoparticles

“…For Ag-rGO-AA composite, no significant reflectance peak is observed, suggesting a nearly complete removal of O-containing group from the GO sheets by the addition of ascorbic acid. Here, the significant reflectance peak which corresponds to C=C sp 2 -hybridized groups is also not observed as expected despite of the aggressive reduction process, which is commonly reported in other literatures (He et al 2014;Li et al 2008;Xu et al 2015). Since C=C bonds in Ag-rGO-AA are commonly symmetrical, bond polarity on the C=C groups should not exist.…”

“…Figure 7 shows the chemical reaction between oxygen (O)-containing functional groups on the GO sheets, i.e. epoxide and hydroxyl groups and ascorbic acid in order to enhance the reduction of GO (Xu et al 2015). Both hydroxyl and epoxide groups were decomposed upon reaction with hydrogen (H) atoms in the five pentagonal ring of ascorbic acid to form the rGO with high quantity of C=C bonds with both water (H 2 O) and dehydroascorbic acid as side products.…”