Li Jie-Qiong, Hu Jin-Yuan, Cheng Jun
State Henan Engineering Center of New Energy Battery Materials, Henan D&A Engineering Center of Advanced Battery Materials, College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu 476000, China.
State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Phys Chem Chem Phys. 2023 Nov 1;25(42):29143-29154. doi: 10.1039/d3cp03662f.
The charge migration mechanism across the surface heterojunction constructed on an anatase TiO nanocrystal is still under debate. To solve this longstanding question, we present a systematic study of the band edges ( standard hydrogen electrode, SHE) of aqueous TiO interfaces with anatase (101), (100) and (001) surfaces, using a combination of density functional theory-based molecular dynamics (DFTMD) and efficient computational SHE (cSHE) methods. Our calculations show that the conduction band minimum (CBM) of the (101) surface is lower than that of (001) and (100) surfaces, which is thermodynamically favorable for electrons migrating to the (101) surface through the surface heterojunction, while the hole preferentially accumulates on the (100) surface due to its highest valence band minimum (VBM). In addition, we qualitatively explore the facet-dependent photocatalytic activity of anatase TiO. Due to the possession of both the beneficial atomic structure (with 100% undercoordinated Ti atoms at the surface) and electronic structure (more strongly oxidizing holes in the VBM and efficient electron-hole spatial separation separation), the (001) surface exhibits the most efficient photocatalytic performance for water oxidation. Furthermore, it is confirmed that the use of simplified theoretical models neglecting the detailed atomic structures of water at the aqueous interface is inadequate to predict the band alignment of semiconductors relative to water redox potentials, so that it may result in substantial errors in evaluating the photocatalytic performance of materials to be used for water splitting.
锐钛矿型TiO纳米晶体表面异质结上的电荷迁移机制仍存在争议。为了解决这个长期存在的问题，我们结合基于密度泛函理论的分子动力学（DFTMD）和高效计算标准氢电极（cSHE）方法，对具有锐钛矿（101）、（100）和（001）表面的水性TiO界面的能带边缘（标准氢电极，SHE）进行了系统研究。我们的计算表明，（101）表面的导带最小值（CBM）低于（001）和（100）表面，这在热力学上有利于电子通过表面异质结迁移到（101）表面，而空穴由于其最高的价带最小值（VBM）优先积累在（100）表面。此外，我们定性地探索了锐钛矿型TiO晶面依赖性的光催化活性。由于具有有益的原子结构（表面100%的低配位Ti原子）和电子结构（VBM中氧化性更强的空穴和有效的电子-空穴空间分离），（001）表面表现出最有效的水氧化光催化性能。此外，已证实使用忽略水在水界面详细原子结构的简化理论模型不足以预测半导体相对于水氧化还原电位的能带排列，因此在评估用于水分解的材料的光催化性能时可能会导致重大误差。
