Charge Carriers Cascade in a Ternary TiO2/TiO2/ZnS Heterojunction: A DFT Study,ChemCatChem

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Charge Carriers Cascade in a Ternary TiO2/TiO2/ZnS Heterojunction: A DFT Study
ChemCatChem ( IF 3.8 ) Pub Date : 2020-03-04 , DOI: 10.1002/cctc.201902351
Giovanni Di Liberto ₁ , Sergio Tosoni ₁ , Gianfranco Pacchioni ₁

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Composite materials whose band alignment induces a favorable separation of photogenerated electrons and holes often reveal a stronger photocatalytic activity compared to their separate components. As shown by experiments, titania composites display a heterojunction between the anatase (101)‐(001) surfaces, where the former stabilizes electrons and the latter the holes. In principle, an even more efficient carriers separation is achieved if a third component with high hole‐stabilizing capability, ZnS(110), is growth on anatase (001). However, even though this ternary TiO₂/TiO₂/ZnS composite material displays good photoactivity, it does not overperform the TiO₂/TiO₂ one. In this paper an explanation of this evidence is provided by means of periodic hybrid DFT calculations, showing how Coulomb forces play a role against the separation of charge carriers predicted based on the relative energy of the band edges. This highlights the necessity to explicitly account for structural and electronic junction's effects, as well as charge carriers’ localization.

中文翻译：

三元TiO2 / TiO2 / ZnS异质结中的电荷载流子级联：DFT研究

与能带分开取向的复合材料相比，能带取向引起光生电子和空穴的有利分离通常显示出更强的光催化活性。如实验所示，二氧化钛复合材料在锐钛矿（101）-（001）表面之间显示异质结，前者稳定电子，而后者稳定电子。原则上，如果锐钛矿（001）上生长具有高空穴稳定能力的第三种成分ZnS（110），则可以实现更有效的载流子分离。然而，即使这种三元TiO ₂ / TiO ₂ / ZnS复合材料显示出良好的光活性，它也不会表现出TiO ₂ / TiO ₂一。在本文中，通过周期性混合DFT计算提供了这一证据的解释，显示了库仑力如何对基于带边相对能量预测的电荷载流子的分离起反作用。这强调了必须明确考虑结构和电子结的影响以及电荷载流子的局部化的必要性。

更新日期：2020-04-22

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