Mixed Valence Tin Oxides as Novel van der Waals Materials: Theoretical Predictions and Potential Applications
Mixed Valence Tin Oxides as Novel van der Waals Materials: Theoretical Predictions and Potential Applications
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DOI：
10.1002/aenm.201501190
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发表时间：
2016
影响因子：
27.8
通讯作者：
Junjie Wang;N. Umezawa;H. Hosono
中科院分区：
文献类型：
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作者：
Junjie Wang;N. Umezawa;H. Hosono
货车德瓦耳斯（vdW）异质结构，它可以通过以精确选择的顺序组合二维原子晶体来组装，使得在光电子学、光电子学和微电子学中具有广泛的潜在应用。然而，孤立原子面的剥离困难和不同材料之间的晶格失配是阻碍vdW材料获得更多实际应用的主要障碍。在这项工作中，混合价锡氧化物，SnxOy（0.5 < x/y < 1），被提出作为vdW材料的新成员，这些混合价锡氧化物显示出克服上述障碍的希望。将密度泛函理论计算与进化算法相结合，预测了一系列先前报道的氧化锡（Sn 2 O3，Sn 3 O 4，Sn 4 O 5和Sn 5 O 6），未报道的组成（Sn 7 O 8，Sn 9 O 10和Sn 11 O 12）以及新的β-SnO相的晶体结构。这些结构由β-SnO、Sn 2 O3和Sn 3 O 4单层组成。它们的带隙可以通过适当地堆叠单层而在1.56-3.25 eV范围内设计。带隙线性依赖于层间距离，如从层间Sn 2 +-Sn 2+和层内Sn 2 +-O相互作用所理解的。SnxOy结构表现出高的光吸收系数和光激发H2释放的合适带边位置;这表明在光伏和光催化应用中环境友好的太阳能转换的潜力。
Van der Waals (vdW) heterostructures, which can be assembled by combining 2D atomic crystals in a precisely chosen sequence, enable a wide range of potential applications in optoelectronics, photovoltaics, and photocatalysis. However, the difficulty of peeling isolated atomic planes and the lattice mismatch between different materials is the main obstacle to hinder vdW materials from more practical applications. In this work, the mixed valence tin oxides, SnxOy (0.5 < x/y < 1), are proposed as a new member of vdW materials and these mixed valence tin oxides show promise to overcome the above‐mentioned obstacle. Density‐functional theory calculations are combined with an evolutionary algorithm to predict the crystal structures of a series of previously reported tin oxides (Sn2O3, Sn3O4, Sn4O5, and Sn5O6), unreported compositions (Sn7O8, Sn9O10, and Sn11O12), and a new β‐SnO phase. These structures consist of β‐SnO, Sn2O3, and Sn3O4 monolayers. Their band gaps can be engineered in the 1.56–3.25 eV range by stacking the monolayers appropriately. The band gap depends linearly on the interlayer distance, as understood from interlayer Sn2+–Sn2+ and intralayer Sn2+–O interactions. SnxOy structures exhibit high photoabsorption coefficients and suitable band‐edge positions for photoexcited H2 evolution; this indicates potential for environmentally benign solar energy conversion in photovoltaic and photocatalytic applications.