چكيده به لاتين
With increasing power and energy demands in various applications in recent decades, the future world will face the inevitable lack of energy resources crisis. In addition, the gases released due to the consumption of fossil fuels cause severe environmental pollution. This crisis will be solved by replacing renewable energies. Therefore, in order to use these resources, suitable systems for their energy storage should be considered. Supercapacitors have higher power density and lower energy density than second-type batteries and fuel cells, but usually have limited energy density values. TiO2 has attracted many researchers due to its high stability, excellent electrochemical properties, non-toxicity and cost-effectiveness. However, having low electrical conductivity, it is usually necessary to combine TiO2 with other materials such as advanced carbon materials like carbon nanotubes, graphene, etc., in order to achieve the desired properties. Graphene has a hexagonal lattice structure that allows easy transfer of electrons and ions. In this study, TiO2-graphene nanocomposite with variable percentages of graphene (2.5, 5, 10 and 20%wt.) was synthesized using an easy and low-cost hydrothermal method. Then the microstructure, morphology and composition were studied by XRD, FTIR, Raman, Fe-SEM and TEM. In the XRD spectrum of the pure TiO2 sample and the nanocomposite sample, the peaks related to the anatase phase, which is the best titanium oxide phase in terms of electrical properties, were clearly seen. Also, the Raman graph obtained from the nanocomposite sample showed the characteristic peaks of graphene. In this way, the hybridization and the correctness of the synthesis were ensured. Also, the electrochemical behavior of the supercapacitor were investigated by CV, GCD using a three-electrode setup with 1 M H2SO4 electrolyte. Finally, by comparing the electrochemical properties of the electrodes obtained from different nanocomposites and the pure sample, the optimal sample was obtained. Among all of them, the 20 wt% nanocomposite achieved the highest specific capacity value of 623.8 F/g in 2 A/g. Also, this nanocomposite was able to maintain 93.3% of the initial specific capacity after 2000 charge-discharge cycles, and this indicates the high reversibility. In addition, TiO2-20wt% GO shows better performance than all samples in terms of energy density and power density. Therefore, TiO2-graphene nanocomposite can be considered a suitable candidate as an electrode material in energy storage devices.
