Energy-driven surface evolution in beta-MnO2 structures

作     者：Wentao Yao Yifei Yuan Hasti Asayesh-Ardakani Zhennan Huang Fei Long Craig R. Friedrich1 Khalil Amine Jun Lu Reza Shahbazian-Yassar1 

作者机构：Department of Mechanical Engineering-Engineering Mechanics Michigan Technological University Houghton Michigan 49931 USA Chemical Science and Engineering Division Argonne National Laboratory 9700 South Cass Avenue Argonne Illinois 60439 USA Department of Mechanical and Industrial Engineering The University of Illinois at Chicago Chicago Illinois 60607 USA 

出 版 物：《Nano Research》 (纳米研究（英文版）)

年 卷 期：2018年第11卷第1期

页      面：206-215页

核心收录：

学科分类：0710[理学-生物学] 07[理学] 08[工学] 09[农学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：support from the National Science Foundation Partial funding for Y. F. Y. from Argonne National Laboratory the JEOL JEM-ARM200CF in the Electron Microscopy Service (Research Resources Center, UIC) the UIC JEOL JEM-ARM200CF supported by a MRI-R2 grant from the National Science Foundation support from China Scholarship Council (CSC) 

主　　题：manganese oxide facet evolution oriented attachment growth mechanism surface energy 

摘      要：Exposed crystal facets directly affect the electrochemical/catalytic performance of MnO2 materials during their applications in supercapacitors, rechargeable batteries, and fuel cells. Currently, the facet-controlled synthesis of MnO2 is facing serious challenges due to the lack of an in-depth understanding of their surface evolution mechanisms. Here, combining aberration-corrected scanning transmission electron microscopy （STEM） and high-resolution TEM, we revealed a mutual energy-driven mechanism between beta-MnO2 nanowires and microstructures that dominated the evolution of the lateral facets in both structures. The evolution of the lateral surfaces followed the elimination of the {100} facets and increased the occupancy of {110} facets with the increase in hydrothermal retention time. Both self-growth and oriented attachment along their {100} facets were observed as two different ways to reduce the surface energies of the beta-MnO2 structures. High-density screw dislocations with the 1/2〈100〉 Burgers vector were generated consequently. The observed surface evolution phenomenon offers guidance for the facet-controlled growth of beta- MnO2 materials with high performances for its application in metal-air batteries, fuel cells, supercapacitors, etc.