Motivated by the enormous importance of nanoscale TiO₂ in a wide range of photocatalytic applications and the ill-understood high activity of the commercial nano-TiO₂ photocatalysts, we provide a predictive map of how the anatase–rutile level alignment varies from the smallest nanoparticles (NPs) to the bulk. Specifically, we compute the size dependence of the energies of vacuum-referenced electronic levels in a range of realistically structured rutile and anatase TiO₂ NPs employing accurate all-electron density functional calculations. In agreement with most recent work, a staggered type II anatase level alignment is predicted for the bulk phases, which we further find to persist into the regime of large NPs. We predict that other level alignments will emerge when the diameter of the TiO₂ NPs is reduced below ∼15 nm. Our results suggest how experiment could test the widely debated importance of the bulk-like type II anatase level alignment for enhanced photoactivity of nano-TiO₂.

中文翻译：

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金红石和锐钛矿型TiO ₂纳米颗粒之间的尺寸依赖性能级排列：对光催化的影响

受到纳米级TiO ₂在广泛的光催化应用中的巨大重要性以及商业化的纳米TiO ₂光催化剂认识不足的高活性的推动，我们提供了锐钛矿-金红石能级排列与最小的纳米粒子之间如何变化的预测图（NPs）。具体来说，我们计算了一系列实际结构化的金红石和锐钛矿型TiO ₂中真空基准电子能级的能量的尺寸依赖性NP采用精确的全电子密度泛函计算。与最近的工作相一致，预测了大部分相的交错型II型锐钛矿水平比对，我们进一步发现该相将继续存在于大NP的体系中。我们预测，当TiO ₂ NPs的直径减小到约15 nm以下时，将出现其他能级取向。我们的研究结果表明，实验如何能够测试广泛争议的块状II型锐钛矿水平比对提高纳米TiO ₂光敏性的重要性。