Shape and morphology effects on the electronic structure of TiO(2) nanostructures: from nanocrystals to nanorods.
Shape and morphology effects on the electronic structure of TiO(2) nanostructures: from nanocrystals to nanorods.
复制标题
DOI：
10.1021/am404293x
复制
发表时间：
2014-02
影响因子：
9.5
通讯作者：
F. Nunzi;L. Storchi;M. Manca;R. Giannuzzi;G. Gigli;F. De Angelis
中科院分区：
文献类型：
--
作者：
F. Nunzi;L. Storchi;M. Manca;R. Giannuzzi;G. Gigli;F. De Angelis
我们对形状定制锐钛矿型TiO2结构中电子阱态的性质和分布进行了精确的计算分析，研究了形貌对电子结构的影响。通过DFT计算，研究了长度为6 nm的线性纳米晶体模型，这些模型具有不同的形貌，可以重现扁平和细长的条形TiO2纳米晶体，以阐明晶体面百分比对纳米晶体电子结构的影响，特别是关于陷阱态的能量学和分布。假设能量呈指数分布，计算出的导带边缘以下的态密度与实验电容数据很好地拟合。我们的计算结果与实验现象学很好地吻合，表明具有较高（100）和（101）面比值的细长棒状纳米晶体表现出相对较深的陷阱态分布。我们的研究结果指出了纳米晶体形态对陷阱态密度的关键作用，强调了在单个TiO2纳米晶体中低能（101）和高能(100)/(001)表面表面之间平衡的重要性。
We carry out an accurate computational analysis on the nature and distribution of electronic trap states in shape-tailored anatase TiO2 structures, investigating the effect of the morphology on the electronic structure. Linear nanocrystal models up to 6 nm in length with various morphologies, reproducing both flattened and elongated rod-shaped TiO2 nanocrystals, have been investigated by DFT calculations, to clarify the effect of the crystal facet percentage on the nanocrystal electronic structure, with particular reference to the energetics and distribution of trap states. The calculated densities of states below the conduction band edge have been very well fitted assuming an exponential distribution of energies and have been correlated with experimental capacitance data. In good agreement with the experimental phenomenology our calculations show that elongated rod-shaped nanocrystals with higher values of the ratio between (100) and (101) facets exhibit a relatively deeper distribution of trap states. Our results point at the crucial role of the nanocrystal morphology on the trap state density, highlighting the importance of a balance between the low-energy (101) and high-energy (100)/(001) surface facets in individual TiO2 nanocrystals.