First-principles investigation of atomic structures and stability of proton-exchanged layered sodium titanate
First-principles investigation of atomic structures and stability of proton-exchanged layered sodium titanate
复制标题
DOI：
10.1103/physrevb.79.144117
复制
发表时间：
2009-04
影响因子：
3.7
通讯作者：
M. Mori;Y. Kumagai;K. Matsunaga;I. Tanaka
中科院分区：
文献类型：
--
作者：
M. Mori;Y. Kumagai;K. Matsunaga;I. Tanaka
用第一性原理计算方法研究了钛酸钠$({\text{Na}}_{2\ensuremath{-}x}{\text{H}}_{x}{\text{Ti}}_{3}{\text{O}}_{7})$，的原子结构和离子取代.利用实验热力学数据测定的超晶胞总能量和离子化学势，分析了离子交换生成能。实验发现，即使在碱性溶液条件下，也可以发生离子取代。此外，层间结合强度随着${\Text{Na}^{+}$替换${\Text{H}^{+}$的增多而降低，这与层状钛酸盐纳米管形成前${\Text{Ti}_{3}{\Text{O}}_{7}$片状层间剥离事件的$p\Text{H}$效应有关。
Atomic structures and ionic substitutions in sodium titanate $({\text{Na}}_{2\ensuremath{-}x}{\text{H}}_{x}{\text{Ti}}_{3}{\text{O}}_{7})$, having ${\text{Ti}}_{3}{\text{O}}_{7}$ sheetlike layers with ${\text{Na}}^{+}$ and ${\text{H}}^{+}$ in between, were investigated by first-principles calculations. The formation energies via ion exchange of ${\text{Na}}^{+}$ and ${\text{H}}^{+}$ were analyzed by using the supercell total energies and ionic chemical potentials determined with the aid of experimental thermodynamic data. It was found that ionic substitutions of ${\text{Na}}^{+}$ by ${\text{H}}^{+}$ take place even in alkaline solution conditions as found in previous experiments. In addition, the bonding strength between the ${\text{Ti}}_{3}{\text{O}}_{7}$ layers tends to decrease with more ${\text{Na}}^{+}$ substitutions by ${\text{H}}^{+}$, which is related to $p\text{H}$ effects on exfoliation events of ${\text{Ti}}_{3}{\text{O}}_{7}$ sheetlike layers from layered titanate prior to the nanotube formation.