Atomic Imaging of Molybdenum Oxide Nanowires with Unique and Complex Periodicity by Advanced Electron Microscopy

Yi-Hsin Ting; Chun-Wei Huang; Akira Yasuhara; Sheng-Yuan Chen; Jui-Yuan Chen; Li Chang; Kuo-Chang Lu; Wen-Wei Wu

doi:10.1021/acs.nanolett.9b03510

Atomic Imaging of Molybdenum Oxide Nanowires with Unique and Complex Periodicity by Advanced Electron Microscopy

Nano Lett. 2020 Mar 11;20(3):1510-1516. doi: 10.1021/acs.nanolett.9b03510. Epub 2019 Nov 20.

Authors

Yi-Hsin Ting¹, Chun-Wei Huang², Akira Yasuhara³, Sheng-Yuan Chen⁴, Jui-Yuan Chen¹, Li Chang¹, Kuo-Chang Lu⁴, Wen-Wei Wu^{1

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Affiliations

¹ Department of Materials Science and Engineering, National Chiao Tung University, No. 1001, University Road, East District, Hsinchu City 30010, Taiwan.
² Material and Chemical Research Laboratories, Nanotechnology Research Center, Industrial Technology Research Institute, No. 195, Section 4, Chung Hsing Road, Chutung, Hsinchu City 31040, Taiwan.
³ EM Application Department of EM Business Unit, JEOL Ltd, 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan.
⁴ Department of Materials Science and Engineering, National Cheng Kung University, No. 1, University Road, Tainan City 70101, Taiwan.
⁵ Center for the Intelligent Semiconductor Nano-System Technology Research, National Chiao Tung University, Hsinchu 300, Taiwan.
⁶ Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 300, Taiwan.

PMID: 31725308
DOI: 10.1021/acs.nanolett.9b03510

Abstract

Crystalline Mo₅O₁₄ exhibits distinctive structural features such as tunnel structure and pseudolamellar arrangement according to the ideal model. However, the spatial resolution of the conventional technique of transmission electron microscopy (TEM) is insufficient to distinguish the actual positions of atoms. In this work, we aimed to systematically analyze and identify the Mo₅O₁₄ nanowires fabricated by the chemical vapor deposition (CVD) process. Utilizing high-angle annular dark-field (HAADF), annular bright-field (ABF), and enhanced annular bright-field (E-ABF) within the scanning transmission electron microscope (STEM) mode reveals the structural features at the atomic scale. In addition, the ultrahigh resolution images have confirmed the crystallographic insights in [001] growth direction for the Mo₅O₁₄ nanowires with a tunnel structure throughout the nanowire. The cross-sectional images show the unique close-packed plane and atomic arrangement with a network of MoO₆ octahedra and MoO₇ pentagonal bipyramids. These results are consistent with the theoretical atomic arrangement, supporting the realization of Mo₅O₁₄-type catalysts used in the selective oxidation process and battery applications.

Keywords: Mo5O14 structure; atomic arrangement; atomic-resolution STEM; pseudolamellar structure; tunnel structure.