@article{Yao2018, 
author = {Wentao Yao and Yifei Yuan and Hasti Asayesh-Ardakani and Zhennan Huang and Fei Long and Craig R. Friedrich and Khalil Amine and Jun Lu and Reza Shahbazian-Yassar},
title = {Energy-driven surface evolution in beta-MnO2 structures},
year = {2018},
journal = {Nano Research},
volume = {11},
number = {1},
pages = {206-215},
keywords = {manganese oxide, facet evolution, oriented attachment, growth mechanism, surface energy},
url = {https://www.sciopen.com/article/10.1007/s12274-017-1620-5},
doi = {10.1007/s12274-017-1620-5},
abstract = {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.}
}