二氧化锰纳米棒的水热合成与电化学性能研究

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0.1 mL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。

Hydrothermal Synthesis and Electrochemical Characterization of Manganese Dioxide Nanorods

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.