水热合成制备Al掺杂α-MnO2纳米管及其超级电容器电化学性能

通过水热法制备了未掺杂α-MnO₂和Al 掺杂α-MnO₂, 对产物的形貌、结构和电化学性能进行了研究. 扫描电镜(SEM)和高分辨透射电镜(HRTEM)观察表明制备产物呈纳米管形态. 紫外-可见光谱分析计算了产物的能带间隙: 随着Al 的掺杂, α-MnO₂的能带间隙值降低. 以未掺杂α-MnO₂与Al 掺杂α-MnO₂作为电极材料, 通过循环伏安(CV)和恒流充放电测试电极的超级电容器性能. 在50 mA·g^-1电流密度下, 未掺杂α-MnO₂与Al 掺杂α-MnO₂电极的比电容分别达到了204.8 和228.8 F·g^-1. 电化学阻抗谱(EIS)分析表明Al 的掺杂降低了α-MnO₂在电解液中的阻抗, 有利于提高其电化学比电容. 增强的比电容及在1000个循环后仍具有良好的容量保持率,使Al 掺杂α-MnO₂在超级电容器中具有较好的应用前景.

Hydrothermal Synthesis of Al-Doped α-MnO2 Nanotubes and Their Electrochemical Performance for Supercapacitors

α-MnO₂ and Al-doped α-MnO₂ were synthesized via a hydrothermal method. The morphologies, structures, and electrochemical performances of as-synthesized un-doped and doped α-MnO₂ were studied. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) show that these un-doped and doped α-MnO₂ are nanotube shaped. The band gaps of α-MnO₂ are investigated by ultraviolet-visible absorption spectroscopy, which indicates that the band gap of α-MnO₂ decreases upon Al doping. The electrochemical performances of un-doped and doped α-MnO₂ as electrode materials for supercapacitors were measured by cyclic voltammetry (CV) and galvanostatical charge/discharge tests. The specific capacitances of un-doped and Al-doped α-MnO₂ respectively reach 204.8 and 228.8 F·g^-1under a current density of 50 mA·g^-1. It was discovered that the electrochemical impedance of Al-doped α-MnO₂ was decreased by Al doping analyzed using electrochemical impedance spectra (EIS), which provides a beneficial increase to its electrochemical specific capacitance. Enhanced specific capacitance and preferable cycling stability (up to 1000 cycles) for Al-doped α-MnO₂ mean that these systems are favorable prospects for application in supercapacitors.