Document Type

Article

Publication Date

2008

DOI

10.1155/2008/763706

Publication Title

Journal of Nanomaterials

Volume

2008

Issue

763706

Pages

1-8

Abstract

A new method for preparing black birnessite nanoparticles is introduced. The initial synthesis process resembles the classical McKenzie method of preparing brown birnessite except for slower cooling and closing the system from the ambient air. Subsequent process, including wet-aging at 7° C for 48 hours, overnight freezing, and lyophilization, is shown to convert the brown birnessite into black birnessite with complex nanomorphology with folded sheets and spirals. Characterization of the product is performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N(2) adsorption ( BET) techniques. Wet-aging and lyophilization times are shown to affect the architecture of the product. XRD patterns show a single phase corresponding to a semicrystalline birnessite-based manganese oxide. TEM studies suggest its fibrous and petal-like structures. The HRTEM images at 5 and 10 nm length scales reveal the fibrils in folding sheets and also show filamentary breaks. The BET surface area of this nanomaterial was found to be 10.6 m2/g. The TGA measurement demonstrated that it possessed an excellent thermal stability up to 400 °C. Layer-structured black birnessite nanomaterial containing sheets, spirals, and filamentary breaks can be produced at low temperature (-49 ° C) from brown birnessite without the use of cross-linking reagents.

Comments

Copyright © 2008 Marcos A. Cheney et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Original Publication Citation

Cheney, M.A., Bhowmik, P.K., Qian, S.Z., Joo, S.W., Hou, W.S., & Okoh, J.M. (2008). A new method of synthesizing black birnessite nanoparticles: From brown to black birnessite with nanostructures. Journal of Nanomaterials, 2008(763706), 1-8. doi: 10.1155/2008/763706

ORCID

0000-0002-0179-678X (Qian)

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