Preparation Of Mesoporous Manganese Oxides-based Material Via Lyotropic Liquid Crystalline Templates And Its Application

Mesoporous materials have been extensively studied for applications in fuel cells, sensors, batteries, and electrochemical capacitors because of the combination of high surface area and periodic nanostructure. Recently, the lyotropic liquid crystalline phases of surfactants are widely used as templates to prepare mesoporous materials due to the rich polymorphism and long-range periodicities of structures. The repeat distances of mesostructure range from 2 to 10 nanometers. Using the lyotropic liquid crystalline phases, mesoporous platinum, tin, palladium, cobalt, nickel, selenium, tellurium and some semiconductor films have been obtained. In this thesis, the latest development of lyotropic liquid crystalline templated mesoporous materials was reviewed. Based on liquid crystalline template, we obtained mesoporous manganese oxides and Co, Ni-doped manganese oxides films through electrochemical deposition technology. By using chemical precipitation route, we got mesoporous manganese oxides via liquid crystalline template, the capacitance of mesoporous materials are much larger than bulk ones.1. Based on the different surfactant liquid crystalline templates, mesoporous manganese oxides films were synthesized by electrodeposition method. The average pore diameter of mesoporous materials is about 7nm. It is confirmed by polarized optical microscopy, low-angle X-ray diffraction and scanning electrical microscopy that the mesoporous films copy the structure of lyotropic liquid crystalline phase. We compared the electrochemical properties among the Brij56 deposited mesoporous films, P123 deposited films and F127 deposited ones, and we found Brij56 deposited films have the best capacitance properties. We also have a conclusion that the films treated at 200℃have the largest capacitance.2. Using Brij56 as template, mesoporous manganese oxide-based mixed oxides (XMO) films were deposited on the substrate by cyclic voltammetry method. The specific capacitance (SC) of mesoporous XMO films electrosynthesized through Brij56 lyotropic liquid crystalline template are much better than the ones directly electrosynthesized from aqueous solution, respectively, especially the Co-doped mixed oxides electrode. After charge/discharge 500 cycles, the capacitance value remains about 83% of that of the first cycle.3. By using P123 and Brij56 as template, we got the mesoporous manganese oxides via redox chemical precipitation method. The specific capacitance of mesoporous material is larger than the one got from aqueous solution directly, and the diameter of pore is larger than the one synthesized by electrochemical method.