假电容
拉曼光谱
氧化还原
氧气
材料科学
密度泛函理论
电子结构
氧化法
反应性(心理学)
化学
电容
化学工程
物理化学
无机化学
计算化学
超级电容器
有机化学
替代医学
病理
工程类
物理
光学
医学
电极
作者
Lijin Yan,Cheng Shen,Lengyuan Niu,Mao‐Cheng Liu,Jianhua Lin,Taiqiang Chen,Yinyan Gong,Xinjuan Liu,Shiqing Xu
出处
期刊:Chemsuschem
[Wiley]
日期:2019-07-03
卷期号:12 (15): 3571-3581
被引量:52
标识
DOI:10.1002/cssc.201901015
摘要
Abstract Defect engineering is an effective way to modulate the intrinsic physicochemical properties of materials. In this work, δ‐MnO 2 with oxygen vacancies is fabricated by a simple oxidation or reduction process, and the relationship between the electronic structure and pseudocapacitance is systematically studied through experimental analysis and theoretical calculations. The peaks in the Raman spectra of the as‐prepared samples are shifted compared with those of pure MnO 2 and the Mn 3+ /Mn 4+ ratio and O species content also change after the introduction of oxygen vacancies. The optimized samples exhibit a better specific capacitance of 207 F g −1 after the oxidation process and 181.4 F g −1 after the reduction treatment compared with only 143.9 F g −1 for the pure MnO 2 . The samples obtained through the oxidation or reduction process also retain 93.3 or 86.4 % of the initial capacity after 5000 cycles. The excellent properties are attributed to the enhanced conductivity and increased surface reactivity or electrochemically active sites. Theoretical calculations demonstrate that the presence of oxygen vacancies leads to an increase in the density of states, which improves the redox reaction of MnO 2 . This study will provide a reference for exploring and designing highperformance pseudocapacitive materials.
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