二氧化锰纳米棒的水热合成与电化学性能研究

Hydrothermal Synthesis and Electrochemical Characterization of Manganese Dioxide Nanorods

在酸性条件下直接水热分解高锰酸钾合成了二氧化锰纳米棒，用XRD、TEM／SAED和SEM／EDAX等方法对所得产物进行了分析和表征，系统研究了水热反应温度、酸用量、酸种类以及搅拌对所得产物晶相和形貌的影响，分析了水热分解高锰酸钾过程中锰的价态变化及二氧化锰的形成过程。结果表明，纯相的二氧化锰纳米棒可在一个较宽的温度范围内（100～150℃）合成；酸的用量和种类对所得MnO2的晶体结构和形貌有一定影响，当浓H2SO4用量少于0．1mL时得到了层状MnO2产物，而当使用浓H3PO4时则得到了α—MnO2和MnPO4·H2O的混合物。同时考察了所制备的二氧化锰纳米棒在碱性锌锰电池中的放电性能，并与文献中已报道过的结果和商用电解二氧化锰的电化学性能进行了比较。

MnO2 nanorods were synthesized by direct hydrothermal decomposition of KMnO4 under acidic conditions. XRD, TEM/SAED and SEM/EDAX were used to analyze and characterize the products. The effects of hydrothermal temperatures, usage of sulfuric acid, kinds of acids, and stirring on the phases and morphologies were systematically investigated. The change of Mn valence and formation of MnO2 nuclei during the hydrothermal decomposition of KMnO4 were analyzed based on the XRD data. The results show that pure phase MnO2 nanorods can be obtained in a broad hydrothermal temperature range （ 100 - 150 ℃ ）. The usage and kind of acids have a certain effect on the crystal structures and morphologies of the resulted MnO2. Layer-structured MnO2 products are obtained when the usage of H2SO4 is less than 0.1 mL while a mixture of α-MnO2 and MnPO4 · H2O are achieved when dense H3PO4 was used. The discharge characteristics of the prepared MnO2 nanorods in alkaline Zn-MnO2 batteries were studied and compared with the reported data in the literature and the electrochemical property of commercial EMD.