Showing 2 results for Reduced Graphene Oxide
H. Darrudi, M. Adelifard,
Volume 16, Issue 1 (3-2019)
Abstract
In this paper we have investigated the physical properties of reduced graphene oxide (RGO) thin films prepared at various substrate temperatures of 230, 260, 290, 320 and 350 oC using spray pyrolysis technique. We have compared these films from various viewpoints, including structural, morphological, optical, electrical and thermos-electrical properties. XRD analysis showed a phase shift from graphene oxide (GO) to RGO due to elevate the substrate temperature from 200 oC to higher temperatures. FESEM images of RGO thin films reveal that a stacked image of irregular and folding nanosheets, and rod-like features at temperatures below and above 290 oC; respectively. Optical studies showed that the layers have a relatively high absorption coefficient (∼0.8×104 to 1.7×104 cm−1) in the visible range, with an optical band gap of 1.67–1.88 eV. The Hall effect data showed that all samples have a p-type conductivity with a hole concentration of ∼1015 cm−3, and sheet resistance values of about 106 Ω/sq, in agreement with previous reports. The thermoelectric measurements revealed that with increasing applied temperature gradient between the two ends of the samples, the thermoelectric electromotive force (emf) of the prepared RGO thin films increases.
Z. Abasali Karaj Abad, A. Nemati, A. Malek Khachatourian, M. Golmohammad,
Volume 17, Issue 4 (12-2020)
Abstract
The graphene oxide -TiO2 (GO-TiO2) and pre-reduced graphene oxide -TiO2 (rGO-TiO2) nanocomposites were fabricated successfully by hydrothermal method. The microstructure of synthesized nanocomposites was investigated using field emission scanning electron microscopy (FESEM) equipped with energy dispersive spectroscopy (EDS) analysis. Moreover, galvanostatic charge/discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) methods in three electrode system were applied to evaluate electrochemical properties. The results revealed that nanoparticles distributed more uniformly on graphene sheets, at lower concentrations of TiO2. The rGO-TiO2 and GO-TiO2 nanocomposites showed 224 and 32 F/g specific capacitance at 5 mV s-1 scan rate in 1 M KOH aqueous electrolyte, respectively. The pre-reduction of graphene oxide is the main reason for the better electrochemical performance of rGO-TiO2 nanocomposite compared to GO-TiO2 nanocomposite.
