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Ceria (CeO 2 ) nanoparticles were grown on reduced graphene oxide (RGO) via the in situ reduction of graphene oxide (GO) in the presence of cerium nitrate and CTAB, followed by a one step hydrothermal treatment. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy (RS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the samples. The characterization suggests that the ammonia-assisted hydrothermal method is a facile and advantageous route to synthesize CeO 2 -RGO nanocomposites compared to the widely used method utilising hydrazine hydrate as the reducing reagent. TEM investigations revealed that the CeO 2 nanoparticles with an average size of $14 nm were dispersed on the layers of RGO. The catalytic activity of the CeO 2 -RGO nanocomposites towards the electrooxidation of hydrazine was further investigated by cyclic voltammetry measurements. The results obtained suggest that compared to bare CeO 2 nanoparticles, the CeO 2 -RGO nanocomposite exhibits remarkably enhanced electrocatalytic activity, due to the synergistic effects between the CeO 2 nanoparticles and RGO.

A simple and effective method for the preparation of water dispersible graphene using sulfonated poly(ether-ether-ketone) (SPEEK) has been described. The SPEEK macromolecules are noncovalently adsorbed on the surface of graphene through π-π interactions. The SPEEK-modified graphene (SPG) forms an aqueous dispersion that is stable for more than six months. An analysis of the ultraviolet-visible spectra shows that the aqueous dispersion of SPG obeys Beer's law and the molar extinction coefficient has been found to be 149.03 mL mg(-1) cm(-1). Fourier transform infrared, Raman, and X-ray photoelectron spectroscopy analyses confirm successful reduction and surface modification of graphene. An atomic force microscopy (AFM) analysis reveals the formation of a single layer of functionalized graphene. Transmission electron microscopy results are also in good agreement with the AFM analysis and support the formation of single-layer graphene. SPG shows good electrochemical cyclic stability during cyclic voltammetry and charge/discharge process when used as a supercapacitor electrode. A specific capacitance of 476 F g(-1) at a current density of 6.6 A g(-1) is observed for SPG materials.

Synthesis of reduced graphene oxide (RGO) from graphite oxide (GO) usually involves the use of some harmful reducing agents. Here, we report a simple approach for the reduction of GO at room temperature using a mixture of potassium iodide and hydrochloric acid. The reduction of GO involves (a) iodide mediated epoxide ring-opening, resulting in hydroxyl groups and dehydration to the corresponding olefins, (b) hydroxyl group substitution by iodide ions, and (c) elimination of iodide ions on the surface. The as-synthesized RGO has an electrical conductivity of 1251 S m À1 and an excellent electrocatalytic activity. The electrocatalytic activity of RGO towards the electrochemical reduction of oxygen and the oxidation of hydrazine was investigated. The RGO-based electrode showed pronounced electrocatalytic activity towards the reduction of oxygen and the oxidation of hydrazine in 0.1 M KOH. At alkaline pH, the reduction of oxygen and oxidation of hydrazine were observed at À0.35 and 0.5 V, respectively. In comparison with the bare glassy carbon (GC) electrode, a spectacular decrease in the overpotential and considerable increase in the oxidation peak current for hydrazine were observed on the RGO-based electrode without using any redox mediator. The RGO-based platform is highly sensitive towards the electrochemical oxidation of hydrazine and reproducible results were obtained. Moreover, the RGO-based electrode showed excellent operational and long time storage stabilities. The sensitivity of the electrode was calculated to be 0.137 AE 0.02 mA mM À1 .

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