An Investigation on Preparation and Property of Manganese Dioxide–polymer Composite Material by Cyclic Voltammetry
|Course||Physical and chemical|
|Keywords||Cyclic Voltammetry Composite Electrode Manganese Dioxide Electronically Conducting Polymers Specific Capacitance Oxygen Reduction Reaction|
As an important electrode material, owing to its such unique properties as low price, large specific area, resource abundance, environmental friendliness, steady electrochemical characteristic, high specific capacitance and excellent reversibility, manganese dioxide has been extensively utilized in neutral zinc, primary and secondary alkaline, as well as lithium/manganese cells. Whereas because of its inferior electrochemical activity, MnO2 resource runs out gradually, therefore chemists are focusing on the modification of MnO2 electrode material.In this thesis, on the basis of manganese dioxide preparation through CV technique, the influence of scan rate on the obtained manganese dioxide was discussed. The difference of deposition method of manganese dioxide was compared. The doped effect of manganese dioxide with two typical electronically conducting polymers (ECPs): PANI (polyaniline) and PPy (polypyrrole) was investigated. And we reach major results and conclusions below.1、Manganese dioxide was successfully deposited on a graphite substrate at room temperature via CV (cyclic voltammetry). The number of electron transferred was calculated according to the results of cyclic voltammograms at different scan rates and diffusivity value of Mn(Ⅱ). The EC (electrochemical-chemical) reaction mechanism of MnO2-deposition on a graphite electrode was inferred, basically in accordance with literature. Results obtained from electrochemical techniques demonstrate that the area-based specific capacitance of this composite decreases with scan rate. This material has excellent charge-storage ability and good electrocatalysis for ORR (oxygen reduction reaction). And for the first time, the dynamic model of catalysis for ORR was established.2、Manganese dioxide was successfully deposited on a graphite substrate at room temperature via various electrochemical techniques other than CV, such as chronopotentiometry, chronoamperometry and potentiostatic methods. Controlled morphologies of manganese dioxide were acquired shown by SEM (scanning electron microscopy).3、Manganese dioxide/polyaniline composite film materials were successfully fabricated on a graphite substrate at room temperature via CV. Results obtained from SEM images show MnO2-PANI chain structure and Mn peak of EDS (energy dispersive x-ray spectrometer) element analysis illustrates the formation of Mn on a graphite electrode originates from deposited MnO2. Thermo gravimetric analysis demonstrates the excellent thermal steadiness of Manganese dioxide/polyaniline composite.4、Manganese dioxide/polypyrrole composite film materials were successfully fabricated on a graphite substrate at room temperature via CV. Results obtained from CV measurements demonstrated that this composite has excellent charge-storage ability. Chronopotentiograms demonstrate the excellent reversibility of the materials. Finally this product was employed to ORR, and results obtained from CVs demonstrate that this composite has enhanced electrocatalysis for ORR when compared to the pure PPy.