Characteristics of Graphene Oxide Films Reduced by Using an Atmospheric Plasma System.

Chii-Rong Yang,Shih-Feng Tseng,Yu-Ting Chen

doi:10.3390/nano8100802

Abstract

The chemical oxidation method can be used to mass-produce graphene oxides (GOs) from highly oriented pyrolytic graphite. However, numerous oxygen-containing functional groups (hydroxyl, epoxy, carbonyl, etc.) exist in typical GO surfaces, resulting in serious electrical losses. Hence, GO must be processed into reduced graphene oxide (rGO) by the removal of most of the oxygen-containing functional groups. This research concentrates on the reduction efficiency of GO films that are manufactured using atmospheric-pressure and continuous plasma irradiation. Before and after sessions of plasma irradiation with various irradiation times, shelters, and working distances, the surface, physical, and electrical characteristics of homemade GO and rGO films are measured and analyzed. Experimental results showed that the sheet resistance values of rGO films with silicon or quartz shelters were markedly lower than those of GO films because the rGO films were mostly deprived of oxygen-containing functional groups. The lowest sheet resistance value and the largest carbon-to-oxygen ratio of typical rGO films were approximately 90 Ω/sq and 1.522, respectively. The intensity of the C–O bond peak in typical rGO films was significantly lower than that in GO films. Moreover, the intensity of the C–C bond peak in typical rGO films was considerably higher than that in GO films.

Highlights

Graphene is a single layer of carbon atoms with a two-dimensional hexagonal lattice structure
Many methods have been proposed for fabricating graphene materials, including micromechanical cleavage of highly oriented pyrolytic graphite (HOPG) [12], epitaxial growth method [13], chemical vapor deposition (CVD) [3], electrochemical exfoliation of HOPG [14], light exfoliation [15], chemical exfoliation [16], and reduction of graphene oxide (GO) [17]
After the X-ray photoelectron spectroscopy (XPS) analysis, an oxygen/carbon atomic ratio (O/C) of GO samples reduced from 38% down to 10% between the thermal treatment temperature of 300 ◦C and 1050 ◦C

Summary

Introduction

Graphene is a single layer of carbon atoms with a two-dimensional hexagonal lattice structure. Ramesha and Sampath [19] utilized electrochemical reduction to produce rGO from oriented GO films This method can be used to reduce GO by applying a DC bias voltage from 0 to −1 V. To meet requirements for the low cost, simple process, easy control reduction area, and mass production for rGO films, this study aimed to develop a novel thermal reduction method for GO films using an atmospheric-pressure plasma system. Because this process can produce rGO films under atmospheric pressure and without vacuum, this process could reduce manufacturing costs, could be operated, and could streamline the maintenance of associated manufacturing equipment. The sheet resistance values of GO and rGO films were measured using a four-point probe instrument

Experimental Details

Electrical Resistance Analysis

Findings

Conclusions