Effects of covalent surface modifications on the electrical and electrochemical properties of graphene using sodium 4-aminoazobenzene-4′-sulfonate

• Published in: Carbon (New York) 2013-04, Vol.54, p.310-322
• Main Authors: Yu, Dong Sheng, Kuila, Tapas, Kim, Nam Hoon, Khanra, Partha, Lee, Joong Hee
• Format: Article
• Language: English
• Subjects: Capacitance; Carbon; Cross-disciplinary physics: materials science; rheology; Electrode materials; Exact sciences and technology; Graphene; Materials science; Other materials; Physics; Reduction; SAS; Sodium; Specific materials; X-ray photoelectron spectroscopy
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2012.11.043

The broad application of graphene is impeded by its intrinsically insoluble property. Therefore, two types of water dispersible graphene were synthesized by the reaction of graphene oxide (GO) with sodium 4-aminoazobenzene-4′-sulfonate (SAS) and its aryl diazonium salt (ADS). The maximum dispersibilities of SAS- and ADS-functionalized graphene (SAS-G and ADS-G) in water were 1.4 and 2.9mgmL−1, respectively. Fourier transform infrared, Raman and X-ray photoelectron spectroscopy (XPS) revealed successful surface modification of graphene using SAS and ADS. The electrical conductivity of ADS-G (1120Sm−1) was much greater than SAS-G (149Sm−1), which is attributed to two-step reduction of GO to graphene. Thermogravimetric analysis revealed that excess surface modifier was attached to the surface of the ADS-G compared to SAS-G, which corroborates the Raman and XPS analysis. The electrochemical properties of the formed SAS-G and ADS-G were investigated, and the results demonstrated that ADS-G showed better specific capacitance (210Fg−1) than SAS-G (170Fg−1). All these observations confirmed that the surface modified graphene can be used as energy storage electrode materials because of their high specific capacitance values.