MnO2/H-TiO2纳米异质阵列的调控制备及超电容特性

采用目标调控的阳极氧化工艺制备了超大比表面、管与管相互分离的有序TiO₂纳米管阵列（TiO₂ NTAs）基体，进而分别采用电化学氢化法和循环浸渍沉积法对晶化退火后的TiO₂ NTAs实施电化学氢化和高比电容MnO₂沉积的双重功能化改性，调控构筑了一种新型MnO₂/H-TiO₂纳米异质阵列电极材料。利用场发射扫描电子显微镜（FESEM）、高分辨透射电子显微镜（TRTEM）、X射线衍射仪（XRD）、X光电子能谱仪（XPS）、拉曼光谱（Raman）和电化学工作站等对样品进行综合表征与超电容特性测试，结果表明：电化学氢化改性有效提高了H-TiO₂ NTAs的导电性和电化学特性，当电流密度为0.2 mA·cm^-2时H-TiO₂ NTAs的面积电容达到7.5 mF·cm^-2，是相同电流密度下TiO₂ NTAs的75倍；经过2个浸渍循环所获得的MnO₂/H-TiO₂ NTAs-2样品在电流密度为3 mA·mg^-1时比电容可达481.26 F·g^-1，电流密度为5 mA·mg^-1时循环充放电1000圈后比电容仅下降约11%。

Controlled Synthesis and Supercapacitive Performance of Heterostructured MnO2/H-TiO2 Nanotube Arrays

This study used the target-controlled anodizing process for the controllable fabrication of TiO₂ nanotube arrays (TiO₂ NTAs) film substrate with large specific surface area and well-separated nanotubes. After annealing crystallization, TiO₂ NTAs were successively functional modified by electrochemical hydrogenation and sequential chemical bath deposition of high specific capacitance MnO₂ nanoparticles onto both the outer and inner surfaces of the nanotubes, thus constructing the heterostructured MnO₂/H-TiO₂ NTAs electrode. The as-prepared samples were fully characterized by field emission scanning electron microscopy (FESEM), highresolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy. The supercapacitive performance and stability of the resulting samples were systematically evaluated using electrochemical workstation. The results from the current study revealed that conductivity and electrochemical properties of H-TiO₂ NTAs were dramatically enhanced through electrochemical hydrogenation and the specific capacitance of H-TiO₂ NTAs could achieve 7.5 mF·cm^-2 at current density of 0.2 mA·cm^-2, which is almost 75 times the performance of TiO₂ NTAs (0.1 mF·cm^-2). Furthermore, the specific capacitance of MnO₂/H-TiO₂ NTAs-2 could achieve 481.26 F·g^-1 at a current density of 3 mA·mg^-1 as well as outstanding long-term cycling stability with only 11% reduction of initial specific capacitance at a current density of 5 mA·mg^-1 after 1000 cycles.