Electrochemical application of all-chemically synthesized graphene/iron oxide composites

Graphene is a one-atom thick structure composed of sp2 hybridized carbons arranged in a two-dimensional hexagonal reticulum, presenting unique properties, such as exceptional charge transport and optical properties, which give great applicability in different areas. In this work, we report the applications of the total chemically-synthesized graphene from benzene, obtained as thin films at liquid-liquid interface. The samples were fully characterized and a set of samples were prepared varying i) post-synthesis treatment (without treatment, HCl and NH4OH-treated), and ii) the number of layer of thin film deposited on the substrate for electrochemical tests: cyclic Voltammetry (CV) and charge and discharge (CD) to evaluate the applicability of graphene/iron oxide composites in electrochemical devices. In the cyclic voltammetry tests we studied two electrolytes, different potential window and scan speeds. The CV tests showed cathodic and anodic peaks relative to redox processes of iron species present in the film, and showed voltammogram area increasing with the deposition, indicating a rise in the capacitance of the material. The CD tests showed a characteristic capacitor profile for all samples, and from these tests it was possible to determine the capacitance values. Figure 1 shows the studied samples composed by 2 layers film. The sample without treatment after the synthesis presented the best results in higher current densities, with values of capacitance up to 30 F g-1. Thus, the sample without post treatment has been shown to be the most promising samples to applications in capacitors.