A density functional theory study of polarons on different TiO_(2) surfaces  

不同二氧化钛表面极化子的密度泛函理论研究

作　　者：SHI Zhiqun GONG Xueqing 石智群;龚学庆(华东理工大学化学与分子工程学院计算化学中心,上海200237;上海交通大学化学化工学院,上海200240)

机构地区：[1]Centre for Computational Chemistry,School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China [2]School of Chemistry and Chemical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China

出　　处：《燃料化学学报（中英文）》2024年第12期1877-1888,I0011-I0013,共15页Journal of Fuel Chemistry and Technology

摘　　要：Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of controversy.This study delves into the formation of polarons in different crystalline forms of TiO_(2) and their connection with the materials'structure.By employing density functional theory calculations with on-site Coulomb interaction correction(DFT+U),we provide a detailed analysis of the electronic polarization behavior in the anatase and rutile forms of TiO_(2).We focus on the polarization properties of defect-induced and photoexcited excess electrons on various TiO_(2) surfaces.The results reveal that the defect electrons can form small polarons on the anatase TiO_(2)(101)surface,while on the rutile TiO_(2)(110)surface,both small and large polarons(hybrid-state polarons)are formed.Photoexcited electrons are capable of forming both small and large polarons on the surfaces of both crystal types.The analysis indicates that the differences in polaron distribution are primarily determined by the intrinsic properties of the crystals;the structural and symmetry differences between anatase and rutile TiO_(2) lead to the distinct polaron behaviors.Further investigation suggests that the polarization behavior of defect electrons is also related to the arrangement of electron orbitals around the Ti atoms,while the polarization of photoexcited electrons is mainly facilitated by the lattice distortions.These findings elucidate the formation mechanisms of different types of polarons and may contribute to understanding the performance of TiO_(2)in different fields.极化子被广泛认为在材料的电荷传输和光催化性能中起着至关重要的作用,但其形成机制和潜在的驱动因素仍然是一个有争议的问题。本研究探讨了TiO_(2)不同晶型中极化子的形成及其与材料结构的联系。通过采用密度泛函理论计算和在位库仑相互作用校正(DFT+U),对TiO_(2)锐钛矿型和金红石型的电子极化行为进行了分析。专注于两种TiO_(2)表面上缺陷诱导和光激发产生的过量电子的极化特性。结果表明,缺陷电子可以在锐钛矿型TiO_(2)(101)表面形成小极化子,而在金红石型TiO_(2)(110)表面,同时形成小极化子和大极化子(杂化态极化子)。光激发电子能够在两种晶型的表面上形成小极化子和大极化子。分析表明,极化子分布的差异主要由晶体的固有性质决定的;锐钛矿和金红石型TiO_(2)之间结构和对称性的差异导致了不同的极化子行为。进一步的研究表明,缺陷电子的极化行为也与Ti原子周围电子轨道的排列有关,而光激发电子的极化主要由高能量电子跃迁导致的晶格畸变促成。这些发现阐明了不同类型极化子的形成机制,有助于理解TiO_(2)在不同领域的性能。

关 键 词：POLARON surface defect PHOTOEXCITATION TiO_(2) density functional theory 

分 类 号：TQ134.1[化学工程—无机化工]