Preparation And Functionalization Of New Manganese Oxide Materials To Explore

With the rapid development of modern society, energy and environment problem have aroused more and more attention, however, new approaches and chances to solve these problems are provided by the fast development of nanoscience and nanotechnology. Manganese oxides with excellent properties have wide applications in various fields, such as catalysts, absorbers, ion exchange, communication, microwave ferrite, soft magnetic ferrite, gas sensor, humidity sensor, and many other fields. However, the present methods used in preparation of manganese oxides still show some disadvantages. For example, there are still significant challenges in designing manganese oxides with high surface areas, strong thermal stability, controllable shape and size. Meanwhile, the functionalities of different manganese oxides are still needed to be developed, such as photonic, electronic, catalytic and adsorbing properties. The present work developed several new approaches for preparing different manganese oxides with the aim to expand their applications. The detailed works are discribed as follows:(1) Preparation of Mn2O3/SBA-15 by NH3 evaporation induced hydrolysisManganese oxides were anchored into the mesporous SBA-15 by a new, simple, and efficient NH3 evaporation induced hydrolysis. The catalyst exhibited high surface and well ordered mesoporous structure, which could be attributed to smooth hydrolysis of the pre-dispersed manganese precursor inside the pores of SBA-15. The catalytic performances the as-prepared are Mn2O3/SBA-15 were examined during H2O2 oxidative degradation of MB and ethanol, which showed that the 50% Mn2O3 loading was the optimum. Meanwhile, the influences of pH and reaction temperature on the catalytic efficiencies were also studied, which showed the benefits of the increased temperature and the decreased pH value.(2) Preparation of MnOx with controllable structures by KMnO4 oxidation of carbonMnO2 with layer and 2×2 tunnel structure was prepared by KMnO4 oxidation of carbon at low temperature. The influences of the reaction time, temperature, pH and reactant concentration were studied. The products were well characterized by powder X-ray diffraction, transmission electron microscopy and field-emission scanning electron microscopy etc. The mechanism for the transform of morphology was proved by tracking the morphology of the product at different reaction conditions. Furthermore, Mn2O3, Mn3O4 and MnO in core-shell structured spheres were successfully obtained by treating MnO2 under different conditions. Functionality tests demonstrated that the core-shell structured MnO2 displayed high electrocapacity while the core-shell structured Mn2O3 exhibited strong adsorption ability. Besides the core-shell structured MnO2 and Mn2O3 both display high activity in catalysis.(3) Low-temperature synthesis of LiMn2O4Core-shell structured LiMn2O4 spheres were synthesized by treating the mixture of MnO2 and LiOH·4H2O at 400oC in N2 and air, respectively. Characterizations of the products are carried out by using powder X-ray diffraction and field-emission scanning electron microscopy.