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This content will become publicly available on May 30, 2019

Title: Large-Scale Synthesis and Comprehensive Structure Study of δ-MnO 2

Layered δ-MnO 2 (birnessites) are ubiquitous in nature and have also been reported to work as promising water oxidation catalysts or rechargeable alkali-ion battery cathodes when fabricated under appropriate conditions. Although tremendous effort has been spent on resolving the structure of natural/synthetic layered δ-MnO 2 in the last few decades, no conclusive result has been reached. In this Article, we report an environmentally friendly route to synthesizing homogeneous Cu-rich layered δ-MnO 2 nanoflowers in large scale. The local and average structure of synthetic Cu-rich layered δ-MnO 2 has been successfully resolved from combined Mn/Cu K-edge extended X-ray fine structure spectroscopy and X-ray and neutron total scattering analysis. It is found that appreciable amounts (~8%) of Mn vacancies are present in the MnO 2 layer and Cu 2+ occupies the interlayer sites above/below the vacant Mn sites. Effective hydrogen bonding among the interlayer water molecules and adjacent layer O ions has also been observed for the first time. These hydrogen bonds are found to play the key role in maintaining the intermediate and long-range stacking coherence of MnO 2 layers. Quantitative analysis of the turbostratic stacking disorder in this compound was achieved using a supercell approach coupled with anisotropic particle-size-effect modeling.more » Furthermore, the present method is expected to be generally applicable to the structural study of other technologically important nanomaterials.« less
Authors:
ORCiD logo [1] ;  [2] ; ORCiD logo [3] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of Kentucky, Lexington, KY (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-205726-2018-JAAM
Journal ID: ISSN 0020-1669
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Name: Inorganic Chemistry; Journal ID: ISSN 0020-1669
Publisher:
American Chemical Society (ACS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; δ-MnO2; birnessite; interlayer water; pair distribution function; neutron diffraction; stacking disorder
OSTI Identifier:
1440358