Preparation And Electrochemical Properties Of Pd And Ag Modified Co₃O₄ Nanowires

Cobalt oxide(Co3O4), as a very important transition metal oxides, has many functional applications, especially in electrochemical aspects. Such as, it can be used for electricity catalyst of Fuel cells and can be used as electrode materials for surpercapacitor and Lithium ion battery. In the present dissertation, CO3O4 nanowire electrodes were synthesized using a non-template synthetic route and modified by electrochemical deposition method in order to improve the electrochemical propertie. Pd-modified Co3O4 nanowires electrode and Ag-modified Co3O4 nanowires electrode were prepared through the above methods and characterized by X-rays diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical performance was investigated by some electro chemical mearuring technologys, such as Cyclic voltammetry (CV) and Electrochemical impedance spectro-scopic (EIS).Pd-modified Co3O4 nanowire electrode was prepared and its performance for hydrogen peroxide electro-reduction in KOH solution was investigated. The results shows that:electrochemical deposition conditions have a big effect on the the performance of the electrode. When PdCl2 concentration was 2.0 mmol·dm-3, sweep speed was 1 mV·s-1 and Scanning lap was 5, Palladium nanoparticles evenly distributed in the Co3O4 nanowires surface and Pd-modified Co3O4 nanowires electrode exhibited high activity and good stability for electrocatalytic reduction of H2O2. A current density of as high as -150 mA·cm-2 was achieved, When hydrogen peroxide concentration was 0.4 mol-dm-3,the potential was-0.4 V. Compared with Co3O4 nanowires electrode, the current density of Pd-modified Co3O4 nanowire electrode was improved dozens of times and the resistance was reduced largely, only to get about 0.3Ω.Ag-modified Co3O4 nanowire electrode was manufactured through the same method. It was found that: The capacitance of Ag/Co3O4 mainly was Faraday Pseudo-capacitance which was produced by the redox reaction of Co3O4. Ag/Co3O4 electrode had a largest capacitance of 1009 F·g-1. When current density was 10 mA-cm'2, the capacitance was 947.5 F·g-1 for the first time and retained 885.9 F·g-1 after 500 cycles. Capacity attenuation rate is only 6.5%. Compared with Co3O4 nanowire electrode, The capacitance was improved from 642.7 F·g-1 to 930.6 F·g-1 and the charge transfer resistance was reduced from 0.35Ωto 0.12Ωbecause of the addition of Ag.