Periodic DFT+D Molecular Modeling of the Zn-MOF-5(100)/(110)TiO2 Interface: Electronic Structure, Chemical Bonding, Adhesion, and Strain

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• 作者：Filip Zasada ; Witold Piskorz ; Joanna Grybo艣 ; Zbigniew Sojka
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 1, 2014
• 年：2014
• 卷：118
• 期：17
• 页码：8971-8981
• 全文大小：543K
• 年卷期：v.118,no.17(May 1, 2014)
• ISSN：1932-7455

文摘

Electronic structure, bonding characteristics, adhesion, and stress energy of the Zn-MOF-5(100)/(110) rutile interface were modeled by using periodic DFT+D calculations, corroborated by simulation of high resolution transmission electron microscopy (HR-TEM) images. Adjustment of the flexible metal鈥搊rganic framework (MOF) moiety to the rigid rutile substrate was achieved within a supercell comprised of (1 脳 1) Zn-MOF-5 and (4 脳 9) TiO₂ units. It was shown that binding of the Zn-MOF-5 layer takes place via bidentate 1,4-benzenedicarboxylate (BDC)鈥搕itania bridges. A coherent interface can be formed with the minimal periodicity along the [11虆0] direction defined by nine Ti_5c adsorption sites (9 脳 2.96 脜 = 26.64 脜) and two consecutive linkers of the Zn-MOF-5 chain (2 脳 12.94 脜 = 25.88 脜). The MOF part is tuned to the oxide substrate by tilting the BDC linkers by 10掳 and twisting around their long axis by 34掳. The resultant lattice strain of the Zn-MOF-5 layer was equal to 蔚_[001] = 0.31% and 蔚_[11虆0] = 2.86%, and the associated stress energy to 蟽_total = 4.8 eV. Pronounced adhesion energy of the Zn-MOF-5 layer deposited on the rutile surface (鈭?.33 eV/nm²) stems from the sizable dispersion (鈭?.39 eV/nm²) contribution, counterbalancing the unfavorable lattice strain and bonds distortion components. The calculated density of states structure of the Zn-MOF-5(100)/(110)TiO₂ interface revealed that it can be described as an electronically coupled, staggered (Type II) charge injection system, where a photoinduced electron may be directly transferred from the Zn-MOF-5 moiety to the conduction band of the titania substrate.