Impact of the degree of functionalization of graphene oxide on the electrochemical charge storage property and metal ion adsorptionElectronic supplementary information (ESI) available: Fig. S1: pictorial presentation of the GO samples prepared. Fig. S2: interlayer spacing for GO samples with different degrees of oxidation. Fig. S3: plot ID/IG ratio for graphite and different GO samples (GO-1 to GO-5). Fig. S4: plot of zeta potential vs. samples with different oxidation levels. Fig. S5: impedance

• Main Authors: Kadam, Mahesh M, Lokare, Omkar R, Kireeti, Kota V. M. K, Gaikar, Vilas G, Jha, Neetu
• Format: Article
• Language: English
• ISSN: 2046-2069
• DOI: 10.1039/c4ra08862j

Graphene oxide (GO) samples were prepared at room temperature using a modified Hummer's method. The quantitative variation of oxidizing agent for the oxidation of graphene sheets resulted in increase of the oxygen functionalities on the GO samples. The qualitative analysis of functional groups and surface charge variation were studied using Fourier transform infra-red (FTIR) spectroscopy and zeta potential, respectively. Different oxidation degrees of GO were investigated by X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS). The electrochemical charge storage properties of the GO samples were studied using a two electrode supercapacitor cell. The fabricated supercapacitor demonstrates linear enhancement in the specific charge storage with an increase in the oxidation of the GO samples. A maximum charge storage of 71 F g −1 has been obtained with the highly oxidized GO sample at room temperature. The adsorption of metal ions from aqueous solution has also been studied with the variation in the degree of functionalization of the GO samples. It was observed that increasing oxygen functionalities from GO-1 to GO-5 amplifies the uptake of metal ions [Cd( ii ) and Cu( ii )]. The experimental data fits well with the Langmuir adsorption model, indicating monolayer adsorption of metal ion on the GO samples. The increase in oxygen functionalities on GO with increasing use of oxidizing agent results in (i) amplification of redox pseudocapacitive current and (ii) improves metal ion adsorption.