Hydrothermal Synthesis of Manganese Oxides with Tunnel Structures
Manganese oxides with tunnel structures, such as hollandites, nsutite (γ-MnO2), and pyrolusite (β-MnO2) were synthesized by the hydrothermal method under mild conditions, 60 to 180°C and autogenous pressures. The materials were prepared by the redox reaction between permanganate ion (MnO 4 − ) and manganous in (Mn2+ ). The type and concentration of counter cation, pH, and temperature were identified as important parameters. Template effects of the counter cations, mainly alkali and alkali earth ions, were observed. By adjusting the pH and temperature, hollandites could be synthesized with a counter cation which has an ionic diameter between 2.3 and 4.6 Å. Otherwise, nsutite and pyrolusite would be formed.
KeywordsManganese Oxide Hydrothermal Synthesis Microporous Material Tunnel Structure Manganese Nodule
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- 4.Giovanoli, R. and Balmer, B. CHIMIA 35: 53, 1981.Google Scholar
- 6.Guyard, A. Bull. Soc. Chim. Fr. 1: 89, 1864.Google Scholar
- 7.Dubois, M. P. Ann. Chem. 5: 411, 1836.Google Scholar
- 9.Maxwell, K. H. and Thirsk, H. R. J. Chem. Soc. 4057, 1955.Google Scholar
- 13.Giovanoli, R. and Fallerer M. CHIMIA 43: 54, 1989.Google Scholar