Wazir Nasrullah, Ding Chunjie, Wang Xianshuang, Ye Xin, Lingling Xie, Lu Tianqi, Wei Li, Zou Bingsuo, Liu Ruibin
Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China.
Guangxi Key Lab of Processing for Nonferrous Metals and Featured Materials and Key lab of new Processing Technology for Nonferrous Metals and Materials, Ministry of Education; Nano and Energy Research Center, School of Physics, Guangxi University, Nanning, 530004, China.
Nanoscale Res Lett. 2020 Aug 1;15(1):156. doi: 10.1186/s11671-020-03386-x.
Molybdenum dioxide (MoO) a kind of semi-metal material shows many unique properties, such as high melting point, good thermal stability, large surface area-to-volume ratio, high-density surface unsaturated atoms, and excellent conductivity. There is a strong connection between structural type and optoelectronic properties of 2D nanosheet. Herein, the rectangular and hexagonal types of thin and thick MoO 2D nanosheets were successfully prepared from MoO powder using two-zone chemical vapor deposition (CVD) with changing the experimental parameters, and these fabricated nanosheets displayed different colors under bright-field microscope, possess margins and smooth surface. The thickness of the blue hexagonal and rectangular MoO nanosheets are ~ 25 nm and ~ 30 nm, respectively, while typical thickness of orange-colored nanosheet is around ~ 100 nm. Comparative analysis and investigations were carried out, and mix-crystal phases were indentified in thick MoO as main matrix through Raman spectroscopy. For the first time, the emission bands obtained in thick MoO nanosheets via a Cathodoluminescence (CL) system exhibiting special properties of semi-metallic and semi-conductors; however, no CL emission detected in case of thin nanosheets. The electrical properties of thin MoO nanosheets with different morphologies were compared, and both of them demonstrated varying metallic properties. The resistance of thin rectangular nanosheet was ~ 25 Ω at ± 0.05 V while 64 Ω at ± 0.05 V was reported for hexagonal nanosheet, and observed lesser resistance by rectangular nanosheet than hexagonal nanosheet.
二氧化钼（MoO）是一种半金属材料，具有许多独特的性质，如高熔点、良好的热稳定性、大的表面积与体积比、高密度的表面不饱和原子以及优异的导电性。二维纳米片的结构类型与光电性能之间存在着紧密的联系。在此，通过改变实验参数，利用两区化学气相沉积（CVD）法从MoO粉末成功制备出了矩形和六边形的薄厚MoO二维纳米片，这些制备的纳米片在明场显微镜下呈现出不同的颜色，具有边缘且表面光滑。蓝色六边形和矩形MoO纳米片的厚度分别约为25 nm和30 nm，而橙色纳米片的典型厚度约为100 nm。进行了对比分析和研究，通过拉曼光谱在以厚MoO为主要基体中识别出了混合晶相。首次通过阴极发光（CL）系统在厚MoO纳米片中获得了具有半金属和半导体特殊性质的发射带；然而，在薄纳米片中未检测到CL发射。比较了不同形貌的薄MoO纳米片的电学性质，它们都表现出不同的金属性质。薄矩形纳米片在±0.05 V时的电阻约为25Ω，而六边形纳米片在±0.05 V时的电阻报告为64Ω，且观察到矩形纳米片的电阻小于六边形纳米片。
