Shape-Controlled Synthesis of 3D Hierarchical MnO2 Nanostructures for Electrochemical Supercapacitors
Shape-Controlled Synthesis of 3D Hierarchical MnO2 Nanostructures for Electrochemical Supercapacitors
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DOI：
10.1021/cg800834g
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发表时间：
2009-01-01
影响因子：
3.8
通讯作者：
Ma, Yanwei
中科院分区：
文献类型：
--
作者：
Yu, Peng;Zhang, Xiong;Ma, Yanwei
采用一种简单的水热方法，在不使用任何模板和表面活性剂的情况下，制备了海胆形状的α-MnO2。在其他条件不变的情况下，当溶液中存在Al3+时，产物为α-MnO2纳米棒团簇；当溶液中的Fe3+取代Al3+时，产物的物相由α-MnO2转变为epsilon-MnO2；海胆状的α-MnO2和α-MnO2纳米棒簇由直径约30-40 nm、长约0.87-1.2微米的单晶MnO2纳米棒组成。这种三维棒状的epsilon-MnO2纳米结构由厚度约为17 nm的纳米片组成。用循环伏安法(CV)和交流阻抗法研究了制备的MnO2材料在水溶液中的电化学性能。三维棒状epsilon-MnO2纳米结构具有120Fg(-1)的比电容和较低的电荷转移电阻。结果表明，金属离子(Fe~(3+)、Al~(3+))对MnO_2的结构和形貌影响很大。
A simple hydrothermal method has been used to fabricate sea urchin shaped alpha-MnO2 without using any template and surfactant. When other conditions were kept the same and Al3+ exists in the solution, the product is alpha-MnO2 nanorods clusters; when Al3+ was substituted by Fe3+ in the solution, the phase of the products was transformed from alpha-MnO2 to epsilon-MnO2; relatively, the morphology of the product was changed from urchinlike clusters to 3D clewlike. The sea urchin shaped alpha-MnO2 and alpha-MnO2 nanorods clusters consist of radially grown single crystalline MnO2 nanorods of ca. 30-40 nm in diameter and ca. 0.87-1.2 mu m in length. The 3D clewlike epsilon-MnO2 nanostructures are composed of nanosheets with a thickness of about 17 nm. The electrochemical properties of the prepared MnO2 materials were studied using cyclic voltammetry (CV) and ac impedance measurements in aqueous electrolyte. 3D clewlike epsilon-MnO2 nanostructures have a specific capacitance of 120 F g(-1) and lower charge-transfer resistance. The results indicate that metal ions (Fe3+, Al3+) have great effects on the structure and morphology of MnO2.