Department of Chemistry , University of Washington , Seattle , Washington 98195-1700 , United States.
Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States.
Nano Lett. 2018 May 9;18(5):3297-3302. doi: 10.1021/acs.nanolett.8b01264. Epub 2018 Apr 30.
Colloidal ZnO semiconductor nanocrystals have previously been shown to accumulate multiple delocalized conduction-band electrons under chemical, electrochemical, or photochemical reducing conditions, leading to emergent semimetallic characteristics such as quantum plasmon resonances and raising prospects for application in multielectron redox transformations. Here, we demonstrate a dramatic enhancement in the capacitance of colloidal ZnO nanocrystals through aliovalent Fe-doping. Very high areal and volumetric capacitances (33 μF cm, 233 F cm) are achieved in ZnFeO nanocrystals that rival those of the best supercapacitors used in commercial energy-storage devices. The redox properties of these nanocrystals are probed by potentiometric titration and optical spectroscopy. These data indicate an equilibrium between electron localization by Fe dopants and electron delocalization within the ZnO conduction band, allowing facile reversible charge storage and removal. As "soluble supercapacitors", colloidal iron-doped ZnO nanocrystals constitute a promising class of solution-processable electronic materials with large charge-storage capacity attractive for future energy-storage applications.
胶体 ZnO 半导体纳米晶体以前被证明在化学、电化学或光化学还原条件下可以积累多个离域导带电子，从而产生出新兴的类金属特性，如量子等离子体共振，并为多电子氧化还原转化的应用提供了前景。在这里，我们通过掺杂变价 Fe 来证明胶体 ZnO 纳米晶体的电容显著增强。在 ZnFeO 纳米晶体中实现了非常高的面容量和体容量（33 μF cm，233 F cm），可与用于商业储能设备的最佳超级电容器相媲美。通过电位滴定和光谱学研究了这些纳米晶体的氧化还原性质。这些数据表明，Fe 掺杂剂的电子局域化和 ZnO 导带内的电子离域之间存在平衡，从而允许易于可逆的电荷存储和去除。作为“可溶性超级电容器”，胶体铁掺杂 ZnO 纳米晶体构成了一类很有前途的溶液处理型电子材料，具有大容量电荷存储能力，适合未来的储能应用。
