钛白（TiO $_2$）由于其光催化分解水的能力而在人工光合作用的研究中起着核心作用。尽管在这一领域进行了40多年的深入研究，但对技术相关的TiO 2 $_2$（101）表面上的第一个水单层的性质仍然存在一些争论。在这项工作中，我们使用第一性原理计算来逆向工程[Walle et al.，J. Phys. Chem. C 115，9545（2011）]，并发现支持在第一单层中存在解离水和分子水的混合物的证据。使用半局部和混合功能的计算，我们修改了目前的理解的吸附能量显示，通过形成一个氢键合的羟基-水络合物的能量成本的水解离降低。我们还表明，这样一个复杂的可以提供一个不寻常的超结构在高分辨率扫描隧道显微镜实验中观察到的解释。
英文摘要：
Titanium dioxide (TiO$_2$) plays a central role in the study of artificial photosynthesis, owing to its ability to perform photocatalytic water splitting. Despite over four decades of intense research efforts in this area, there is still some debate over the nature of the first water monolayer on the technologically-relevant anatase TiO$_2$ (101) surface. In this work we use first-principles calculations to reverse-engineer the experimental high-resolution X-ray photoelectron spectra measured for this surface in [Walle et al., J. Phys. Chem. C 115, 9545 (2011)], and find evidence supporting the existence of a mix of dissociated and molecular water in the first monolayer. Using both semilocal and hybrid functional calculations we revise the current understanding of the adsorption energetics by showing that the energetic cost of water dissociation is reduced via the formation of a hydrogen-bonded hydroxyl-water complex. We also show that such a complex can provide an explanation of an unusual superstructure observed in high-resolution scanning tunneling microscopy experiments.
The efforts in the optimization of the physical and chemical properties related to the photocatalytic efficiency of TiO2 nanoparticles relies mainly on defect engineering strategies, been the structural and the doping the most common ones. The doping of the anatase TiO2 structure with lanthanides elements potentially can turns the TiO2 optical absorption into the visible range increasing drastically its photocatalytic efficiency. Here we show that the processing of TiO2 nanoparticles in oxygen atmosphere and the La doping stabilizes the anatase phase. The La incorporation takes place mainly in…
Electronic and magnetic properties of V-doped anatase TiO$_{2}$ from first principles
采用第一性原理研究了钒掺杂的二氧化钛$_{2}$的几何、电子和磁性。DFT+U（Hubbard系数）方法预测了Ti $_{1-x}$ V $_{x}$ O $_{2}$（x=6.25和12.5%）的半导体能带结构，与样品的低电导率很好地吻合，而广义梯度近似内的标准计算失败。理论结果表明，钒原子倾向于保持接近，并通过超交换相互作用产生强铁磁性。氧空位诱导的磁极化子能使大范围分离的磁性杂质之间产生长程铁磁相互作用。实验观察到的室温下V掺杂的TiO_2 $_{2}$的铁磁性可能源于短程超交换耦合和长程束缚磁极化子逾渗的结合。
Band alignment effects of anatase and rutile nanocrystals in TiO$_2$ powders lead to an electron hole separation, increasing the photo catalytic efficiency of these powders. While size effects and types of possible alignments have been extensively studied, the effect of interface geometries of bonded nanocrystal structures on the alignment is poorly understood. In order to allow conclusive studies of a vast variety of bonded systems in different orientations, we have developed a new density functional tight binding parameter set to properly describe quantum confinement in nanocrystals. Applyin…
In this work, electronic structure of several doped TiO$_2$ anatase systems is computed using DFT+$U$. Effective masses of charge carriers are also computed to quantify how the dopant atoms perturb the bands of the host anatase material. $U$ is computed systematically for all the dopants using the linear response method rather than using fitting procedures to physically known quantities. A combination of $d$ and $f$ block elements (Nb, Ta, V, Mo, W, Cr, La, Cu, Co and Ce) are considered as dopants. Depending upon the energies of their outer $d$ or $f$ electrons, the dopants are found to form d…
We combined scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) experiments with density functional theory (DFT) calculations to study dispersed tungsta clusters on anatase TiO$_2$(101). Following two different preparation methods, we found that monomeric WO$_3$ species are the most stable configuration rather than WO$_3$ trimers, (WO$_3$)$_3$. The WO$_3$ monomers form tetrahedral WO$_4$ structures on anatase TiO$_2$(101), with one W$-$O bond and two W$-$O$-$Ti linkages per WO$_3$ monomer. Locally, the WO$_3$ monomers form well-ordered (2$\times$1) structures. The di…
Quantum Mechanical Process of Carbonate Complex Formation and Large Scale Anisotropy in the Adsorption Energy of CO$_2$ on Anatase TiO$_2$ (001) Surface
CO $_2$在半导体表面上的吸附是其光催化还原的先决条件。由于TiO $_2$具有优良的抗光腐蚀性、无毒性和合适的带边位置，被认为是促进氧化还原反应的最有效的光催化剂。然而，由于缺乏足够的理解的机制的吸附，CO $_2$转换效率的TiO $_2$表面上没有得到最大化。虽然TiO 2 TiO $_2$（101）是最稳定的面，但（001）表面更具反应性，并且实验表明，在氟离子存在下，稳定性可以逆转，并且可以合成更大百分比（高达~ 89%）的（001）面。因此，我们通过密度泛函方法研究了CO $_2$在TiO $_2$（001）表面的吸附.我们已经开发了一个三态量子力学模型，解释了化学吸附的机制，导致形成的三齿碳酸盐复合物。电子结构分析表明，CO $_2$ -TiO $_2$在表面的相互作用是单轴的、长程的，从而导致了结合能的各向异性.它否定了广泛认为的覆盖率和BE之间的一一对应关系，并推断CO $_2$的空间分布主要决定BE。设计了一个概念性实验，其中可以控制CO $_2$浓度和流动方向以在~1.5 eV的大窗口内调谐BE。实验还表明，化学吸附可以达到最大50%的覆盖率。在水的存在下，活化的碳酸盐络合物通过克服约0.9 eV的势垒形成碳酸氢盐络合物。
Comparative Density Functional Theory and Density Functional Tight Binding Study of Arginine and Arginine-Rich Cell-Penetrating Peptide TAT Adsorption on Anatase TiO2
Water absorption and dissociation processes on pristine low-index TiO$_2$ interfaces are important but poorly understood outside the well-studied anatase (101) and rutile (110). To understand these, we construct three sets of machine learning potentials that are simultaneously applicable to various TiO$_2$ surfaces, based on three density-functional-theory approximations. We compute the water dissociation free energies on seven pristine TiO$_2$ surfaces, and predict that anatase (100), anatase (110), rutile (001), and rutile (011) surfaces favor water dissociation, anatase (101) and rutile (10…
The quasiparticle electronic structure and optical excitation of anatase TiO$_2$ is determined within the framework of many-body perturbation theory (MBPT) by combining the $G_0W_0$ method and the Bethe-Salpeter Equation (BSE). A modified version of the HSE06 screened hybrid functional, that includes 20\% exact Fock exchange (HSE06(20)) as opposed to 25\% in the standard HSE06 functional, is used to set up the starting Hamiltonian for $G_0W_0$+BSE calculations. The HSE06(20) functional accurately predicts the ground state electronic band structure. BSE calculations based on data from $G_0W_0$+…
Theoretical insights of codoping to modulate electronic structure of TiO$_2$ and SrTiO$_3$ for enhanced photocatalytic efficiency
TiO $_2$和SrTiO $_3$由于其特殊的电子结构、高化学稳定性、无毒和低成本而在纳米材料领域中是公知的材料。然而，由于宽的带隙，这些只能在UV区域中使用。因此，有必要通过掺杂金属、非金属或不同元素的组合来降低其带隙，从而扩大其在可见光区的光学响应，同时保持光催化效率。我们在这里报告，共掺杂的金属和非金属在SrTiO $_2$和SrTiO $_3$有效的光催化分解水使用混合密度泛函理论和\textit{ab initio}原子热力学。后者确保捕获环境效应，以了解带电缺陷在现实条件下的热力学稳定性。我们已经观察到，带电的缺陷是稳定的，除了中性的缺陷，在TiO_2-$_2$和共掺杂剂作为施主以及受体取决于掺杂的性质（p型或n型）。然而，SrTiO $_3$中最稳定的共掺杂剂主要充当施主。我们的研究结果表明，尽管在可见光区的响应，在TiO $_2$和SrTiO $_3$的共掺杂并不总是提高光催化活性，由于复合中心的形成或导带最低或价带最高的大位移。在各种金属-非金属组合中，Mn $_\textrm{Ti}$ S $_\textrm{O}$（即Mn在Ti位被取代，S在O位被取代），S $_\textrm{O}$在钛酸锰$_2$和Mn $_\textrm{Ti}$ S $_\textrm{O}$中的混合物，SrTiO中的Mn $_\textrm{Sr}$ N $_\textrm{O}…
Anatase TiO$_2$ Nanowires Functionalized by Organic Sensitizers for Solar Cells : A Screened Coulomb Hybrid Density Functional Study
采用标准和区间分离的混合密度泛函理论计算方法研究了矢车菊素葡萄糖苷（C $_{21}$ O $_{11}$ H $_{20}$）和TA-St-CA在纳米线（101）和（001）上的吸附.所得染料-纳米线组合体系的电子结构和光谱显示出这些类型的光致发色团的不同特征。天然染料矢车菊素葡萄糖苷的最低未占分子轨道位于半导体的导带下方，而在TA-St-CA的情况下，它与导带内的状态共振。通过这些染料敏化剂的电子-空穴产生和随后的电荷注入，可以将宽带隙纳米线功能化用于太阳能电池。给体- $π$ -受体型染料TA-St-CA在TiO $_2$表面的吸附大大改变了其分子间电荷转移特性。矢车菊素葡萄糖苷通过其羟基在纳米线上表现出相对较强的锚定作用。染料-纳米线系统的原子结构重新优化与列入非线性溶剂化效应表明，这两种染料的结合强度保持温和，即使在离子溶液中。
