Department of Physics, Hazara University, Mansehra 21300, Pakistan.
Phys Chem Chem Phys. 2018 Oct 7;20(37):24168-24175. doi: 10.1039/c8cp03933j. Epub 2018 Sep 12.
The stacking of monolayers in the form of van der Waals heterostructures is a useful strategy for band gap engineering and the control of dynamics of excitons for potential nano-electronic devices. We performed first-principles calculations to investigate the structural, electronic, optical and photocatalytic properties of the SiC-MX (M = Mo, W and X = S, Se) van der Waals heterostructures. The stability of most favorable stacking is confirmed by calculating the binding energy and phonon spectrum. SiC-MoS is found to be a direct band gap type-II semiconducting heterostructure. Moderate in-plane tensile strain is used to achieve a direct band gap with type-II alignment in the SiC-WS, SiC-MoSe and SiC-WSe heterostructures. A difference in the ionization potential of the corresponding monolayers and interlayer charge transfer further confirmed the type-II band alignment in these heterostructures. Furthermore, the optical behaviour is investigated by calculation of the absorption spectra in terms of ε(ω) of the heterostructures and the corresponding monolayers. The photocatalytic response shows that the SiC-Mo(W)S heterostructures can oxidize HO to O. An enhanced photocatalytic performance with respect to the parent monolayers makes the SiC-Mo(W)Se heterostructures promising candidates for water splitting.
通过范德华异质结构的层层堆叠是一种用于带隙工程和控制激子动力学的有效策略，可用于潜在的纳米电子器件。我们进行了第一性原理计算，以研究 SiC-MX（M=Mo、W 和 X=S、Se）范德华异质结构的结构、电子、光学和光催化性质。通过计算结合能和声子谱来证实最有利的堆叠的稳定性。发现 SiC-MoS 是一种直接带隙 II 型半导体异质结构。通过适度的面内拉伸应变，SiC-WS、SiC-MoSe 和 SiC-WSe 异质结构实现了直接带隙和 II 型对齐。相应单层的电离势和层间电荷转移的差异进一步证实了这些异质结构中的 II 型能带排列。此外，通过计算异质结构和相应单层的 ε(ω)，研究了光学性质。光催化响应表明 SiC-Mo(W)S 异质结构可以将 HO 氧化为 O。与母体单层相比，SiC-Mo(W)Se 异质结构具有增强的光催化性能，使其成为水分解的有前途的候选材料。
