A facile route to fabricate stable reduced graphene oxide dispersions in various media and their transparent conductive thin films

• Published in: Journal of colloid and interface science Vol. 383; no. 1; pp. 36 - 42
• Main Authors: Min, Kyoungho, Han, Tae Hee, Kim, Joohoon, Jung, Jiyoung, Jung, Cheolsoo, Hong, Soon Man, Koo, Chong Min
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.10.2012; Elsevier
• Subjects: ambient temperature; Chemistry; coatings; Dispersions; ethanol; Ethyl alcohol; Exact sciences and technology; General and physical chemistry; Graphene; graphene oxide; hydrazine; Media; Oxides; Reduced graphene oxide (RGO); reducing agents; Reduction; silicon; Silicon substrates; Solubility parameter; Spray coating; Surface physical chemistry; Thin films; Transparent electrode; Zeta potential; Solubility parameter; Reduced graphene oxide (RGO); Zeta potential; Spray coating; Transparent electrode; Film; Alcohol; Dispersant; Oxides; Electrodes; Chemical reduction; Transparent thin film; Alkanol; Surface properties; pH; Polarity; Electrokinetic potential; Silicon; Hydrazine; Polycarbonate; Wafer; Surface potential; Composition; Ethanol; Volatiles; Dispersion; Substrate; Graphene; Graphite; Room temperature
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2012.06.021

[Display omitted] ► We demonstrate an easy way to prepare stable reduced graphene oxide (RGO) dispersions. ► Dispersion stability was controlled by simple adjustment of the degree of reduction and pH. ► Degree of reduction affected the surface polarity of RGO platelets. ► pH affected the surface potential of RGO platelets. ► Transparent conductive RGO thin films on various substrates were prepared using a spray coating. In this paper, we demonstrate an easy way to prepare a stable reduced graphene oxide (RGO) dispersion in aqueous or organic media by simple adjustment of the degree of reduction and pH of RGO dispersion, and a subsequent fabrication of transparent conductive RGO thin films on various substrates using a spray coating technique. RGOs were prepared using a hydrazine reducing agent from graphene oxide (GO), which was oxidized from graphite via a modified Hummers’ method. The degree of reduction determined the surface properties, such as atomic composition, surface polarity, and potential of RGO platelets. In addition, pH significantly affected the surface potential of graphene dispersion. The fine adjustment of degree of reduction and pH of RGO dispersion made production of fine RGO dispersions in aqueous and organic media such as ethanol and DMF possible without any aid of dispersing agents. The stable RGO dispersion using volatile ethanol medium provided a unique advantage to be spray-coated into uniform transparent conductive RGO thin films on various substrates including silicon wafer, flexible polycarbonate film regardless of their surface properties, and even on non-planar substrates such as round-shaped glassware at room temperature.