Mortazavi Bohayra, Shahrokhi Masoud, Javvaji Brahmanandam, Shapeev Alexander V, Zhuang Xiaoying
Chair of Computational Science and Simulation Technology, Department of Mathematics and Physics, Leibniz Universität Hannover, Appelstraße 11, D-30167 Hannover, Germany.
Independent researcher, Lyon, France.
Nanotechnology. 2022 Apr 12;33(27). doi: 10.1088/1361-6528/ac622f.
In the latest experimental success, NbOItwo-dimensional (2D) crystals with anisotropic electronic and optical properties have been fabricated (33 (2021), 2101505). In this work inspired by the aforementioned accomplishment, we conduct first-principles calculations to explore the mechanical, electronic, and optical properties of NbOX(X = Cl, Br, I) nanosheets. We show that individual layers in these systems are weakly bonded, with exfoliation energies of 0.22, 0.23, and 0.24 J m, for the isolation of the NbOCl, NbOBrand NbOImonolayers, respectively, distinctly lower than those of the graphene. The optoelectronic properties of the single-layer, bilayer, and bulk NbOCl, NbOBrand NbOIcrystals are investigated via density functional theory calculations with the HSE06 approach. Our results indicate that the layered bulk NbOCl, NbOBrand NbOIcrystals are indirect gap semiconductors, with band gaps of 1.79, 1.69, and 1.60 eV, respectively. We found a slight increase in the electronic gap for the monolayer and bilayer systems due to electron confinement at the nanoscale. Our results show that the monolayer and bilayer of these novel 2D compounds show suitable valence and conduction band edge positions for visible-light-driven water splitting reactions. The first absorption peaks of these novel monolayers along the in-plane polarization are located in the visible range of light which can be a promising feature to design advanced nanoelectronics. We found that the studied 2D systems exhibit highly anisotropic mechanical and optical properties. The presented first-principles results provide a comprehensive vision about direction-dependent mechanical and optical properties of NbOX(X = Cl, Br, I) nanosheets.
在最新的实验成果中，已制备出具有各向异性电子和光学特性的二维（2D）铌氧化物晶体（《自然通讯》33 (2021), 2101505）。在这项受上述成果启发的工作中，我们进行了第一性原理计算，以探究NbOX（X = Cl、Br、I）纳米片的力学、电子和光学特性。我们表明，这些体系中的单原子层结合较弱，对于NbOCl、NbOBr和NbOI单原子层的剥离能分别为0.22、0.23和0.24 J/m²，明显低于石墨烯的剥离能。通过采用HSE06方法的密度泛函理论计算，研究了单层、双层和体相NbOCl、NbOBr和NbOI晶体的光电特性。我们的结果表明，层状体相NbOCl、NbOBr和NbOI晶体为间接带隙半导体，带隙分别为1.79、1.69和1.60 eV。由于纳米尺度下的电子限域效应，我们发现单层和双层体系的电子带隙略有增加。我们的结果表明，这些新型二维化合物的单层和双层表现出适合可见光驱动水分解反应的价带和导带边缘位置。这些新型单原子层沿面内极化方向的首个吸收峰位于可见光范围内，这对于设计先进的纳米电子器件而言可能是一个有前景的特性。我们发现所研究的二维体系表现出高度各向异性的力学和光学特性。所展示的第一性原理结果为NbOX（X = Cl、Br、I）纳米片与方向相关的力学和光学特性提供了全面的认识。
