چكيده به لاتين
In this project, nanostructures of ferrites, molybdates and tungstates of copper and zinc were synthesized and characterized and their supercapacitor properties were investigated. Ultrasonic method, especially ultrasonic bath method, is an easy, clean and effective method for the preparation of nanostructures, which is intended by default for the synthesis of samples. Also, in some cases, hydrothermal or mecanochemical method has been used to prepare different morphologies of a material and compare their supercapacitor properties with each other. TGA, XRD, XPS, FT-IR, Raman spectroscopy, SEM, TEM, UV-Vis and BET methods were used to characterize the synthesized nanostructures. Electrochemical tests including cyclic voltammetry, galvanostatic charge-discharge, cyclic life and impedance spectroscopy have been used to investigate the supercapacitor properties of the synthesized samples. In addition to electrochemical tests, in order to justify the supercapacitor behavior of the synthesized samples, the morphology, specific surface area and band gap of the synthesized nanostructures, which are important parameters affecting the specific capacitance, have received more attention. To investigate the effect of compositing on the specific capacitance of synthesized nanostructures, graphene composite of copper tungstate nanoparticles was prepared and their specific capacitance and cyclic stability were studied. As it became composite, the specific capacitance of the copper tungstate electrode increased from 254Fg-1 at the current density of 1Ag-1 to 562Fg-1 and its cycle life stability increased by almost 11% after 3000 cycles at the scan rate of 100 mVs-1.
Significant and important actions in this project are the acquisition of nanostructures such as nanofibers, hexagonal nanosheets and spindle-shaped zinc molybdate nanostructures, zinc tungstate nanorods, copper molybdate spherical nanostructures, as well as the preparation of nanoparticles in different dimensions of ferrites, molybdates and tungstates of copper and zinc with new methods and studying and comparison of their supercapacitor properties. In the electrochemical tests of zinc molybdate nanostructures, an electrode made of nanofibers with the specific capacitance of 487 Fg-1 at the current density of 1Ag-1 has the highest specific capacitance, and an electrode made of hexagonal nanosheet after 4000 cycles at scan rate of 100 mVs-1 has the highest cycle life stability while maintaining approximately 95% of the original specific capacitance. Also, the electrochemical test of electrodes made of copper molybdate nanostructures showed that the electrode made of copper molybdate nanoparticles with the specific capacitance of 493 Fg-1 at a current density of 1Ag-1 and a cycle life stability of approximately 92% after 4000 charge-discharge in The current density of 16Ag-1 is more suitable for supercapacitor application than the electrode made of spherical copper molybdate nanostructures with the specific capacitance of 258 Fg-1 and a cycle life stability of approximately 91% under the same conditions. In general, it can be said that in this research, acceptable and promising results have been obtained in comparison with other researches.
