Modulation of band alignment with water redox potentials by biaxial strain on orthorhombic NaTaO3 thin films,Physical Chemistry Chemical Physics

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Modulation of band alignment with water redox potentials by biaxial strain on orthorhombic NaTaO3 thin films
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2020-10-16 , DOI: 10.1039/d0cp04322b
Alexandre Olivieri Kraus _{1,

2,

3,

4} , Guilherme Ribeiro Portugal _{1,

2,

3,

4} , Jeverson Teodoro Arantes _{1,

2,

3,

4}

Affiliation

Photocatalysis-assisted water splitting using semiconductor materials greatly depends on the bandgap size and the alignment of band edges relative to the reaction potentials. We used ab initio computational methods to show that the biaxial strain on [100]-oriented orthorhombic NaTaO₃ thin films grants the modulation of surface states, favoring either the hydrogen evolution reaction (HER) or the oxygen evolution reaction (OER), which basically rules the perovskite photocatalytic performance. Under compression, the outermost TaO₆ and TaO₄ polyhedra become more distorted, and electrostatic repulsion increases the energy of Ta 5d surface states. As they overcome the O₂/H₂O potential, they cease to contribute to the OER. At the same time, the H⁺/H₂ remains below the conduction band, leveraging the HER over the OER. The tensile strain lowers the outermost polyhedra distortions, stabilizing both Ta 5d surface and conduction band states, and increasing the charge centered around surface Ta atoms. Consequently, the bands are better aligned with O₂/H₂O and H⁺/H₂ potentials, which benefits the overall water splitting photocatalysis. Our results evidence that combining facet and strain engineering is an effective way of altering the photocatalytic activity of orthorhombic [100] NaTaO₃ thin films.

中文翻译：

正交晶态NaTaO3薄膜上双轴应变对水氧化还原电位的能带取向的调节

使用半导体材料进行光催化辅助的水分解在很大程度上取决于带隙尺寸和能带边缘相对于反应电势的对准。我们使用了从头算的方法来证明，在[100]取向的正交TaNa ₃薄膜上的双轴应变可以调节表面态，从而有利于氢析出反应（HER）或氧析出反应（OER），基本上决定钙钛矿的光催化性能。在压缩下，最外层的TaO ₆和TaO ₄多面体变得更扭曲，静电排斥增加了Ta 5d表面态的能量。当他们克服O ₂ / H _2时潜在的，他们不再为OER做出贡献。同时，H ⁺ / H ₂保持在导带以下，从而将HER利用OER。拉伸应变降低了最外层的多面体形变，稳定了Ta 5d表面和导带状态，并增加了以表面Ta原子为中心的电荷。因此，这些带更好地与O ₂ / H ₂ O和H ⁺ / H ₂电位对准，这有利于整个水分解光催化。我们的结果证明，将刻面工程和应变工程相结合是改变正交晶[100] NaTaO ₃薄膜的光催化活性的有效方法。

更新日期：2020-10-17

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