School of Chemistry and Chemical Engineering, Guangxi University , Nanning 530004, P. R. China.
ACS Appl Mater Interfaces. 2013 Oct 9;5(19):9508-16. doi: 10.1021/am402257y. Epub 2013 Sep 23.
Pristine and transition-metal-doped Mn3O4 nanocrystals shaped in octahedrons have been synthesized by hydrothermal reduction of potassium permanganate and characterized by SEM/TEM, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical experiments. The results reveal that a multistep reduction process is taking place, and the introduction of doping ions causes a direct synthesis of single-phase Mn3O4 nanocrystals. To assess the properties of Mn3O4 nanocrystals for their use in supercapacitors, cyclic voltammetry and galvanostatic charging-discharging measurements are performed. The phase stability during cycling and charge-transfer behavior are greatly improved by doping with transition metal, and Cr-doped Mn3O4 nanocrystals exhibit a maximum specific capacitance of 272 F g(-1) at a current density of 0.5 A g(-1). These doped Mn3O4 nanocrystals could be a promising candidate material for high-capacity, low-cost, and environmentally friendly electrodes for supercapacitors. In addition, these results have verified the ability of doping to improve capacitive performances of spinel-structured transition-metal oxides.
通过水热还原高锰酸钾，制备了具有八面体形状的纯净和过渡金属掺杂的 Mn3O4 纳米晶体，并通过 SEM/TEM、X 射线衍射、X 射线光电子能谱和电化学实验进行了表征。结果表明，存在多步还原过程，并且掺杂离子的引入导致单相 Mn3O4 纳米晶体的直接合成。为了评估 Mn3O4 纳米晶体在超级电容器中的应用性能，进行了循环伏安法和恒流充放电测量。通过过渡金属掺杂，极大地改善了 Mn3O4 纳米晶体在循环过程中的相稳定性和电荷转移行为，Cr 掺杂的 Mn3O4 纳米晶体在 0.5 A g-1 的电流密度下具有最大比电容 272 F g-1。这些掺杂的 Mn3O4 纳米晶体有望成为用于超级电容器的高容量、低成本和环保电极的有前途的候选材料。此外，这些结果验证了掺杂提高尖晶石结构过渡金属氧化物电容性能的能力。
