Electrochemical synthesis of alpha-MnO2 octahedral molecular sieve

[[abstract]]The alpha-MnO2, octahedral molecular sieve (OMS) with 2 x 2 hollandite-type structure can be electrochemically synthesized with a subsequent self-assembly process at 80degreesC. Powdery OMS material is prepared by the electrochemical oxidation of Mn2+ ion in an acidic medium followed by a hydrolysis reaction. Counter ion effects of H+, Li+, Na+, K+, Cs+ and Mg+2 are studied for the formation of alpha-MnO2 in this self-assembled system. Powder X-ray diffraction (XRD) is used to characterize the relationships among counter ions, electrolysis potential, and phase formation during synthesis. Li-7 nuclear magnetic resonance is used to probe the lithium environment in the hollandite-type structure of the Li+-exchanged and lithiated manganese oxides. (C) 2003 Elsevier Science B.V. All rights reserved.[[note]]SC