钒
氧化还原
无机化学
循环伏安法
化学
电化学
氧气
介电谱
X射线光电子能谱
电极
电化学动力学
玻璃碳
碳纤维
材料科学
化学工程
物理化学
有机化学
复合材料
工程类
复合数
作者
Seong-Cheol Kim,Jihun Paick,Jung S. Yi,Doohwan Lee
标识
DOI:10.1016/j.jpowsour.2021.230813
摘要
Carbon electrodes have long been functionalized with oxygen species to improve their electrocatalytic properties for vanadium redox kinetics in flow batteries. Most reports in the literature describe the oxygen functionalities doped on carbon electrodes as the electrocatalytic active centers for the vanadium redox reactions. Significantly, we offer here critical evidence that the surface defects are the most relevant active centers rather than the doped oxygen species on the carbon electrodes for the intrinsic VO2+/VO2+ and V2+/V3+ redox kinetics. The controlled thermal surface oxygenation and deoxygenation of graphite felt (GF) electrodes with the collective correlation analysis of the electrocatalytic properties as a function of the surface O atomic contents of GF electrodes reveal that the doped oxygen functionalities on carbon electrodes have no critical effects on the intrinsic vanadium redox kinetics. Conversely, the electrocatalytic performance of the GF electrodes correlate with the amount of surface defects concomitantly developed during the thermal oxygen doping processes. The collective structure–property correlation studies with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy show that increasing the surface lattice defects of the carbon electrodes, rather than the amount of doped oxygen functionalities, significantly improves the vanadium redox kinetics.
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