Termination Effects in Aluminosilicate and Aluminogermanate Imogolite Nanotubes: A Density Functional Theory Study
Termination Effects in Aluminosilicate and Aluminogermanate Imogolite Nanotubes: A Density Functional Theory Study
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DOI：
10.3390/cryst10111051
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发表时间：
2020-11
期刊：
影响因子：
2.7
通讯作者：
E. Poli;J. Elliott;Ziwei Chai;G. Teobaldi
中科院分区：
文献类型：
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作者：
E. Poli;J. Elliott;Ziwei Chai;G. Teobaldi
利用半局域和范围校正的混合密度泛函理论（DFT）模拟研究了硅铝酸盐（AlSi）和锗酸铝（AlGe）伊莫戈兰纳米管（NTs）的终止效应.在筛选和识别能够适应几何和静电未扰动核心区域周围NT末端完全松弛的最小有限模型后，我们量化并讨论了物理截断对结构、相对能量、静电和电子性质的影响不同终止的有限尺寸NT模型。除了组成依赖的变化，在价（VB）和导带（CB）的边缘和由此产生的带隙（BG），DFT模拟揭示纵向带弯曲和分离的有限AlSi和AlGe模型。取决于给定的终止的NT，这种纵向效应与径向带分离典型的全周期性的AlSi和AlGe NT的结合表现。AlSi和AlGe NTs中纵向和径向能带弯曲的强烈组合物依赖性表明AlSi和AlGe NTs中光生空穴的产生、弛豫和分离的不同机制，邀请进一步研究伊毛沸石组合物和结构灵活性在光催化应用中的未开发潜力。
We investigate termination effects in aluminosilicate (AlSi) and aluminogermanate (AlGe) imogolite nanotubes (NTs) by means of semi-local and range-corrected hybrid Density Functional Theory (DFT) simulations. Following screening and identification of the smallest finite model capable of accommodating full relaxation of the NT terminations around an otherwise geometrically and electrostatically unperturbed core region, we quantify and discuss the effects of physical truncation on the structure, relative energy, electrostatics and electronic properties of differently terminated, finite-size models of the NTs. In addition to composition-dependent changes in the valence (VB) and conduction band (CB) edges and resultant band gap (BG), the DFT simulations uncover longitudinal band bending and separation in the finite AlSi and AlGe models. Depending on the given termination of the NTs, such longitudinal effects manifest in conjunction with the radial band separation typical of fully periodic AlSi and AlGe NTs. The strong composition dependence of the longitudinal and radial band bending in AlSi and AlGe NTs suggests different mechanisms for the generation, relaxation and separation of photo-generated holes in AlSi and AlGe NTs, inviting further research in the untapped potential of imogolite compositional and structural flexibility for photo-catalytic applications.