Preparation Of Composite Manganese Dioxide By Cyclic Voltammetry And Its Properties Investigation

Manganese dioxide,as one of the important electrode materials,has been widely applied in the neutral zinc-manganese battery,first and second alkaline manganese batteries,as well as lithium/manganese batteries.MnO₂ is the most promising candidate because of its low cost and environmentally benign nature.However,electrochemical property of natural manganese dioxide is poor and in recent years the exploitation of manganese dioxide is enormous,so that the chemical workers pay more attention to high-performance MnO₂ electrode materials.In this paper,on the basis of production of manganese dioxide by cyclic voltmmetry technique,electrodeposited manganese dioxide was modified,manganese dioxide composite materials were applied on the capacitor and the oxygen reduction reaction(ORR).The main results and conclusions can be summarized as following:1.Metal ions of copper(â…¡) and cobalt(â…¡) were doped into MnO₂ by means of cyclic voltammetry(CV).The results demonstrated that the configuration of MnO₂ was influenced by the doped metal ions,the specific capacitance of Cu²⁺-MnO₂ and Co²⁺-MnO₂ are all higher than that of pure MnO₂.2.Manganese dioxide was electrodeposited on the nano-TiO₂ film electrode by cyclic voltammetry technique,the results indicated that MnO₂ was immobilized on the nano-TiO₂ film electrode uniformly,and the developed MnO₂/TiO₂ film electrode has satisfactory cyclic ability and its specific mass capacity amounts to 144.6 F/g,which is higher than the value obtained on the pure MnO₂-modified electrode.3.Manganese oxide was prepared by cyclic voltammetry(CV) technique on a MWCNTs-modified graphite electrode,it was proved that manganese oxide was immobilized onto MWCNTs and a three-dimensional structure modified electrode was generated.The specific capacitance of MnO₂/MWCNTs was improved to be around 6.62×10^-2F/cm²,which is higher than the value obtained on the pure MWCNTs or the pure MnO₂-modified electrode. And then its catalysis for oxygen reduction reaction(ORR) in neutral and alkaline medium was investigated by the electrochemical technique.It was shown that the higher electrocatalysis of MnO₂/MWCNTs for ORR was exhibited when compared to the MWCNTs-modified electrode and MnO₂-modified graphite electrode;especially,the electrocatalysis of MnO₂/MWCNTs towards ORR was increased when the content of OH^- in solution enhanced,and also higher stable catalysis for ORR was exhibited by MnO₂/MWCNTs.This study provides a possibility for MnO₂ and MWCNTs to be used in fuel cells.4.The mechanism of electro-deposition MnO₂ obtained was in accordance with the experiment,and the main results on the deposition behavior of MnO₂ could be summarized as following:(1) In a certain potential range,the potential range of CV has no obvious influence on the deposited MnO₂;(2)The larger Mn(â…¡) concentration,the larger of peak current and peak area and the charge-discharge capacity were obtained;(3) The oxidation of Mn(â…¡) and reduction of Mn(â…¢) were controlled by a mass diffusion process on a GC electrode;(4) Increasing of acid concentration inhibits the formation of MnOOH and favored the stability of Mn(â…¢);(5) When the type of Aniona were changed from the strong acid ion into a weak acid ion, the disproportionation and hydrolysis of Mn(â…¢) was greatly inhibited.