溶胶-凝胶模板法合成MnO_2纳米线

Sol-gel Template Synthesis of MnO_2 Nanowires

本文通过两步阳极氧化在 0 .5M硫酸和 5g L草酸混合溶液中制得多孔氧化铝膜 ,经 5wt%的磷酸扩孔处理得到具有孔径大小均一 ,排列有序 ,并具有一定厚度的阳极氧化铝模板 (AAO) ,以该氧化膜为模板 ,用溶胶 凝胶法在其微孔内合成了MnO2 纳米线。利用扫描电镜 (SEM)对模板和纳米线材料的形貌进行了表征 ,发现氧化铝模板微孔直径为 75± 2nm ,MnO2 纳米线直径在 70nm左右 ,长度为 5 0 0～ 70 0nm。通过X 射线衍射 (XRD)检测可知该纳米线为α MnO2 。循环伏安 (CV)表明α MnO2 纳米线在 2 .0mol L (NH4 ) 2 SO4 溶液中具有优良的电容行为 ,比电容达 1 6 5F g ,是一种理想的超级电容器电极材料。

In this paper, anodic aluminum oxide(AAO) templates with an uniform pore diameter and periodicity were fabricated using a two-step oxidization method in a solution with 0.5M sulfuric and 5g/L oxalic at room temperature, and pore-widening was fulfilled in 5wt% phosphoric acid. Then, arrays of manganese dioxide nanowires were prepared using AAO template above by sol-gel method with a sol-gel solution containing Mn(CH_3COO)_2 and citric acid. SEM characterized the structure of AAO and MnO_2 nanowires. The results show that MnO_2 nanowires with uniform length and diameter were obtained, and the length and diameter of MnO_2 nanowires are dependent on the pore diameter and the thickness of the applied AAO template. The pore diameter of the AAO was about 75±2nm, the diameter of the MnO_2 nanowires was 70nm,and the length of the MnO_2 nanowires was about 500～700nm.XRD analysis indicated the MnO_2 nanowires are α-MnO_2. The results of cyclic voltammetry indicated α-MnO_2 nanowires were a promising electrode material for supercapacitors, the specific capacity of the electrode was 165 F/g.