Formation of Na 0.44 MnO 2 nanowires via stress-induced splitting of birnessite nanosheets

Nano Research (Impact Factor: 7.01). 01/2009; 2(1). DOI: 10.1007/s12274-009-9003-1


High aspect ratio Na 0.44 MnO 2 nanowires with a complex one-dimensional (1 D) tunnel structure have been synthesized. We found that the reaction went through layered birnessite nanosheet intermediates, and that their conversion to the fi nal product involved splitting of the nanosheets into nanowires. Based on our observations, a stress-induced splitting mechanism for conversion of birnessite nanosheets to Na 0.44 MnO 2 nanowires is proposed. The fi nal and intermediate phases show topotaxy with001 f // 020 b or110 b where f represents the fi nal Na 0.44 MnO 2 phase and b the intermediate birnessite phase. As a result of their high surface areas, the nanowires are effi cient catalysts for the oxidation of pinacyanol chloride dye.

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    • "SEM images (Fig. 1(a)) indicated that the shape of the resulting nanocrystals was almost octahedral, but they are tetragonally distorted due to the Jahn–Teller effect on Mn 3+ ions [29]. Edge-shared [MnO 6 ] octahedral units [8] [30] [31] originate from the reaction at the nonbridging hydroxyl groups of adjacent micellar particle surfaces and form a chemical bond. Their construction results in agglomeration of most of the nanocrystals. "
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