Vacancy-induced anion and cation redox chemistry in cation-deficient F-doped anatase TiO2
Vacancy-induced anion and cation redox chemistry in cation-deficient F-doped anatase TiO2
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缺氟掺杂锐钛矿型 TiO2 中空位诱导的阴离子和阳离子氧化还原化学
DOI：
10.1039/d0ta07578g
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发表时间：
2020-10
影响因子：
11.9
通讯作者：
Jianjun Liu
中科院分区：
文献类型：
--
作者：
Haoxin Li;Yining Li;Xiaolin Zhao;Youwei Wang;Kexian Huang;Wujie Qiu;Jifen Wang;Jianjun Liu
将点缺陷如阳离子空位掺入电极材料中被认为是改善电荷转移和离子扩散动力学并允许多价离子插入和迁移的有效策略。然而，它们具有低的比容量和电化学不可逆性。为了阐明这些问题的根源，我们研究了F掺杂和阳离子缺陷的TiO 2通过Mg 2+插入理解空位结构的氧化还原活性。我们的第一性原理计算表明，在空位附近，从阴离子O2−/F−到阳离子Ti 4+的电荷转移是感应发生的，形成氧化的阴离子F（1−x）−/O（2−y）−和还原的阳离子Ti（4−z）+。在Mg ~（2+）插入过程中，还发生了协同的阳离子和阴离子氧化还原反应：Ti ~（3.83 + +0.19）e-→ Ti ~（3.64+），O ~（1.94-+0.06）e-→ O ~（2-）和F ~（0.93-+0.07）e-→ F-。F2 p态氧化后的特殊阴离子氧化还原反应是由低配位的氟离子引起的，这一点已被先前的NMR表征所证实。计算结果表明，氟的氧化还原反应占总氧化还原容量的26.5%。本研究结果为利用空位结构设计开发高效的阳离子和阴离子氧化还原材料，提高电池材料的能量密度和循环稳定性提供了化学线索。
The incorporation of point defects such as cationic vacancies into electrode materials has been considered as an effective strategy to improve the charge-transfer and ion-diffusion kinetics and allow insertion and migration of multivalent ions. However, they suffer from low specific capacity and electrochemical irreversibility. To elucidate the origin of these issues, we investigated the F-doped and cation-deficient anatase TiO2 through Mg2+ insertion for understanding the redox activity of vacancy structure. Our first-principles calculations showed that charge transfer inductively occurs from anion O2−/F− to cation Ti4+ near vacancies, forming oxidized anions F(1−x)−/O(2−y)− and reduced cations Ti(4−z)+. We further found that cooperative cationic and anionic redox reactions, Ti3.83+ + 0.19e− → Ti3.64+, O1.94− + 0.06e− → O2− and F0.93− + 0.07e− → F−, take place during Mg2+ insertion. The peculiar anionic redox reaction of oxidized F 2p states is attributed to low-coordination fluorine ions, which was demonstrated by the previous NMR characterization. Our calculations showed that the fluorine redox reaction contributes 26.5% of the total redox capacity. The present results provided chemical clues to use the vacancy structure design to develop efficient cationic and anionic redox materials for improving the energy density and cyclic stability of battery materials.
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影响因子：
3.2
作者：
Junping Hu;H. Sheng;Qi Deng;Q. Ma;Jun Liu;Xiongwei Wu;Junjie Liu;Yuping Wu
通讯作者：
Junping Hu;H. Sheng;Qi Deng;Q. Ma;Jun Liu;Xiongwei Wu;Junjie Liu;Yuping Wu
影响因子：
41.2
作者：
Koketsu, Toshinari;Ma, Jiwei;Dambournet, Damien
通讯作者：
Dambournet, Damien
影响因子：
3.7
作者：
Kresse, G;Furthmuller, J
通讯作者：
Furthmuller, J
影响因子：
27.8
作者：
A. Urban;Ian L. Matts;A. Abdellahi;G. Ceder
通讯作者：
A. Urban;Ian L. Matts;A. Abdellahi;G. Ceder
影响因子：
10.8
作者：
Koo, Bonil;Xiong, Hui;Shevchenko, Elena V.
通讯作者：
Shevchenko, Elena V.