Center for Nanoscale Materials and Materials Science and Chemistry Divisions, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439.
J Chem Theory Comput. 2005 Jan;1(1):107-16. doi: 10.1021/ct0499635.
The potential of titanium dioxide nanoparticles for advanced photochemical applications has prompted a number of studies to analyze the size, phase, and morphology dependent properties. Previously we have used a thermodynamic model of nanoparticles as a function of size and shape to predict the phase stability of titanium dioxide nanoparticles, with particular attention given to the crossover of stability between the anatase and rutile phases. This work has now been extended to titanium dioxide nanoparticles in water, to examine the effects of various adsorption configurations on the equilibrium shape and the phase transition. Density functional calculations have been used to accurately determine surface energies and surface tension of low index hydrated stoichiometric surfaces of anatase and rutile, which are presented along with a brief outline of the surface structure. We have shown that morphology of TiO2 nanocrystals is affected by the presence of water, resulting in variations in the size of the (001) and (001̄) truncation facets in anatase, and a reduction in the aspect ratio of rutile nanocrystals. Our results also highlight that the consideration of hydrated nanocrystal surfaces is necessary to accurately predict the correct size dependence of the anatase to rutile phase transition.
二氧化钛纳米粒子在先进光化学应用中的潜力促使许多研究对其尺寸、相和形态依赖特性进行了分析。之前，我们已经使用纳米粒子的热力学模型作为尺寸和形状的函数来预测二氧化钛纳米粒子的相稳定性，特别关注金红石相和锐钛矿相之间的稳定性交叉。这项工作现在已经扩展到水中的二氧化钛纳米粒子，以研究各种吸附构型对平衡形状和相变的影响。密度泛函计算已被用于准确确定锐钛矿和金红石低指数水合化学计量表面的表面能和表面张力，同时还简要介绍了表面结构。我们已经表明，水的存在会影响 TiO2 纳米晶体的形态，导致锐钛矿中（001）和（001̄）截断面的尺寸发生变化，以及金红石纳米晶体的纵横比降低。我们的结果还强调，需要考虑水合纳米晶体表面，才能准确预测锐钛矿到金红石相变的正确尺寸依赖性。
