
Article Title
Energy-driven surface evolution in beta-MnO2 structures
Keywords
manganese oxide, facet evolution, oriented attachment, growth mechanism, surface energy
Abstract
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 Burgers vector were generated consequently. The observed surface evolution phenomenon offers guidance for the facet-controlled growth of betaMnO2 materials with high performances for its application in metal-air batteries, fuel cells, supercapacitors, etc.
Graphical Abstract
Publisher
Tsinghua University Press
Recommended Citation
Wentao Yao,Yifei Yuan,Hasti Asayesh-Ardakani,Zhennan Huang,Fei Long,Craig R. Friedrich,Khalil Amine,Jun Lu,Reza Shahbazian-Yassar, Energy-driven surface evolution in beta-MnO2 structures. NanoRes.2018, 11(1): 206–215