Elucidating Ionic Liquid Environments That Affect the Morphology of TiO2 Nanocrystals: A DFT+D Study

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• 作者：Kezhen Qi ; Di Li ; Jiaqi Fu ; Lianjie Zhu ; Xiaochuan Duan ; Qing Qin ; Guichang Wang ; Wenjun Zheng
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：October 9, 2014
• 年：2014
• 卷：118
• 期：40
• 页码：23320-23327
• 全文大小：425K
• ISSN：1932-7455

文摘

Using ionic liquids as controlling agents is known to effectively affect the morphologies of TiO₂ crystals. To obtain a profound understanding of this observation, density functional theory calculations with inclusion of Grimme treatment of the dispersion forces (DFT+D) have been performed to study a typical ionic liquid 1-ethyl-3-methylimidazolium bromide ([Emim]Br) adsorption on the low-index TiO₂ facets, and the equilibrium crystal shape of TiO₂ has been predicted using Wulff鈥檚 rule. [Emim]Br is found to adsorb most strongly on (110) for rutile and (100) for anatase. The gap of surface energy shows an obvious increase after [Emim]Br adsorption, especially, between (101) and (001) for anatase and also between (110) and (001) for rutile. This gap variation results in increasing the (100) facet exposure of anatase, and an increase in the length-to-diameter ratio of rutile nanocrystals, which is verified by our experiments. This study is meaningful to gain further understanding of how ionic liquids achieve shape-controlled nanocrystals synthesis by turning surface chemistry, which will push a valuable step toward the ultimate goal, controlling synthesis of inorganic nanomaterials.