Yang Hua Gui, Sun Cheng Hua, Qiao Shi Zhang, Zou Jin, Liu Gang, Smith Sean Campbell, Cheng Hui Ming, Lu Gao Qing
ARC Centre of Excellence for Functional Nanomaterials, School of Engineering and Australian Institute for Bioengineering and Nanotechnology, Queensland 4072, Australia.
Nature. 2008 May 29;453(7195):638-41. doi: 10.1038/nature06964.
Owing to their scientific and technological importance, inorganic single crystals with highly reactive surfaces have long been studied. Unfortunately, surfaces with high reactivity usually diminish rapidly during the crystal growth process as a result of the minimization of surface energy. A typical example is titanium dioxide (TiO2), which has promising energy and environmental applications. Most available anatase TiO(2) crystals are dominated by the thermodynamically stable {101} facets (more than 94 per cent, according to the Wulff construction), rather than the much more reactive {001} facets. Here we demonstrate that for fluorine-terminated surfaces this relative stability is reversed: {001} is energetically preferable to {101}. We explored this effect systematically for a range of non-metallic adsorbate atoms by first-principle quantum chemical calculations. On the basis of theoretical predictions, we have synthesized uniform anatase TiO(2) single crystals with a high percentage (47 per cent) of {001} facets using hydrofluoric acid as a morphology controlling agent. Moreover, the fluorated surface of anatase single crystals can easily be cleaned using heat treatment to render a fluorine-free surface without altering the crystal structure and morphology.
由于其科学技术重要性，具有高反应性表面的无机单晶长期以来一直受到研究。不幸的是，由于表面能最小化，高反应性表面在晶体生长过程中通常会迅速减少。一个典型的例子是二氧化钛（TiO₂），它在能源和环境应用方面很有前景。大多数现有的锐钛矿TiO₂晶体由热力学稳定的{101}面主导（根据伍尔夫构造，超过94%），而不是反应性更强的{001}面。在这里，我们证明对于氟终止的表面，这种相对稳定性是相反的：{001}在能量上比{101}更有利。我们通过第一性原理量子化学计算系统地研究了一系列非金属吸附原子的这种效应。基于理论预测，我们使用氢氟酸作为形貌控制剂合成了具有高比例（47%）{001}面的均匀锐钛矿TiO₂单晶。此外，锐钛矿单晶的氟化表面可以通过热处理轻松清洁，以获得无氟表面，而不会改变晶体结构和形貌。
