Comparative Studies on Two-Dimensional (2D) Rectangular and Hexagonal Molybdenum Dioxide Nanosheets with Different Thickness.

ABSTRACT: Molybdenum dioxide (MoO₂) 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 MoO₂ 2D nanosheets were successfully prepared from MoO₃ 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 MoO₂ 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 MoO₂ as main matrix through Raman spectroscopy. For the first time, the emission bands obtained in thick MoO₂ 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 MoO₂ nanosheets with different morphologies were compared, and both of them demonstrated varying metallic properties. The resistance of thin rectangular nanosheet was ~ 25 ? at ± 0.05 V while 64 ? at ± 0.05 V was reported for hexagonal nanosheet, and observed lesser resistance by rectangular nanosheet than hexagonal nanosheet.

SUBMITTER: Wazir N 

PROVIDER: S-EPMC7395921 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature