Different Morphology Of Manganese Oxide Nanomaterials Controllable Preparation

Manganese oxide nanomaterials with different structures and morphologies show a wide range of applications in the ion-sieve,molecular sieve,catalyst materials,cathode materials for lithium ion secondary battery and new magnetic materials due to their special physical and chemical properties. Because the electronic and optical properties of the manganese oxide nanomaterials have highly relied on their crystallinity,particle size and particle morphology,it is of great significance to research the controllable fabrication conditions of manganese oxide nanomaterials with different morphologies and to know the relationship between morphology and property.In this paper,we had contrallablly synthesized a series of manganese dioxide nanomaterials with different structures and morphologies.The structure,morphology,and composition of the as-materials had been characterized by XRD,DSC-TGA,SEM,TEM,IR,AAS,elemental analysis and cyclic voltammetry test,and their formation mechanism and electrochemical property had also been studied.This paper mainly consists of two sections,reviewer and experiments.The characteristics and applications of nanomaterials,crystal structure of manganese oxides,shape controllable synthesis status,development trends and application areas of manganese oxide nanomaterials were reviewed in Chapter I.The controllable fabrication of manganese oxides nanomaterials with different structures were described in Chapterâ…¡and Chapterâ…¢.The research conclusion was given in Chapterâ…£.The controllable fabrication of layered manganese oxide nanomaterials with different morphologies is described in alkali solution in Chapterâ…¡.KMnO₄ was used as raw material,layered manganese oxide nanomaterials with nanowire bundle morphology,cotton agglomerate morphology or plate-like morphology,respectively,were controllablly fabricated in the absence of template and catalyst.By changing the reaction temperature,reaction time and the KOH solution concentration, the optimism fabrication parameters of the layered manganese oxide nanomaterials with different morphologies was studied.On the basis of the experimental results,a dissolve-anisotropic growth mechanism for the layered manganese oxide nanomaterials with nanowire bundle morphology and cotton agglomerate morphology had been proposed.The structure and the electrochemical performance of the fabricated layered manganese oxide nanomaterials had been characterized by XRD,DSC-TGA,SEM,TEM,IR,AAS,elemental analysis and cyclic voltammetry method.The results indicated that the layered manganese oxide nanomaterials with different morphologies could be obtained by hydrothermally treating KMnO₄ in alkali solution,and the alkali solution concentration,reaction temperature and reaction time had obvious influence on the morphology of the obtained materials.The layered manganese oxide nanomaterials with nanowire bundle morphology and cotton agglomerate morphology showed a good capacitor performance in Na₂SO₄ solution.The controllable fabrication of manganese oxide nanomaterials with various structures and morphologies was described in Chapterâ…¢.KMnO₄ was used as raw material,the effects of metal cations,H⁺ ions and anions in the reaction system on the structures and morphologies of manganese oxide nanomaterials were investigated systematically.The experimental results indicated that cations in the reaction system played a major role for the formation of manganese oxide nanomaterials with different structures,and K⁺ ions were in competition with H⁺ ions.α-MnO₂ with 2×2 tunnel structure was formed when the amount of K⁺ ions in the reaction system is higher than that of H⁺ ions,while the higher amount of H⁺ ions was favorable for the formation ofβ-MnO₂ with 1×1 tunnel structure. On the other hand,anions in the reaction system did not only influence the structure of manganese oxide nanomaterials,but also influence its morphology.On the basis of the experiment results,the possible formation mechanism of manganese oxide nanomaterials was proposed.