Abstract In this study, we perform a theoretical investigation using the density functional tight-binding (DFTB) approach for the structural analysis and electronic structure of anatase, brookite and rutile phase TiO2 nanoparticles (NPs). Our results show that the number of Ti-O bonds is greater than that of O-O, while the number of Ti-Ti bonds is fewer. Thus, large amounts of O atoms prefer to connect to Ti atoms. The increase in the temperature of the NPs contributes to an increase in the interaction of Ti–O bonding, but a decrease in the O-O bonding. The segregation of Ti and O atoms shows that Ti atoms tend to co-locate at the center, while O atoms tend to reside on the surface. Increasing temperature causes a decrease of the bandgap from 3.59 to 2.62 eV for the brookite phase, which is much more energetically favorable compared to the bulk, while it could increase the bandgap from 3.15 to 3.61 eV for anatase phase. For three-phase TiO2 NPs, LUMO and Fermi levels decrease. The HOMO level of anatase phase NP decreases, but it increases for brookite and rutile phase TiO2 nanoparticles. An increase in the temperature contributes to the stabilization of anatase phase TiO2 NP due to a decrease in the HOMO energies.

中文翻译：

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调整锐钛矿、板钛矿和金红石相 TiO2 纳米粒子的结构特性和电子结构：DFTB 计算

摘要 在本研究中，我们使用密度泛函紧束缚 (DFTB) 方法对锐钛矿、板钛矿和金红石相 TiO2 纳米粒子 (NP) 的结构分析和电子结构进行了理论研究。我们的结果表明，Ti-O 键的数量大于 OO，而 Ti-Ti 键的数量较少。因此，大量的 O 原子更喜欢连接到 Ti 原子。NPs 温度的增加有助于增加 Ti-O 键的相互作用，但会减少 OO 键。Ti 和 O 原子的偏析表明 Ti 原子倾向于共位于中心，而 O 原子倾向于驻留在表面。温度升高导致板钛矿相的带隙从 3.59 eV 降低到 2.62 eV，与体相相比，这在能量上更加有利，而它可以将锐钛矿相的带隙从 3.15 eV 增加到 3.61 eV。对于三相 TiO2 NPs，LUMO 和费米能级降低。锐钛矿相 NP 的 HOMO 水平降低，但板钛矿和金红石相 TiO2 纳米颗粒的 HOMO 水平增加。由于 HOMO 能量的降低，温度升高有助于锐钛矿相 TiO2 NP 的稳定化。