Transformation from Microcrystalline LiMn1-xCrxO2 to 1D Nanostructured -Mn1-xCr<
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- 作者：Dae Hoon Park ; Hyung-Wook Ha ; Sun Hee Lee ; Jin-Ho Choy ; Seong-Ju Hwang
- 刊名：Journal of Physical Chemistry C
- 出版年：2008
- 出版时间：April 3, 2008
- 年：2008
- 卷：112
- 期：13
- 页码：5160 - 5164
- 全文大小：176K
- 年卷期：v.112,no.13(April 3, 2008)
- ISSN：1932-7455
文摘
Cr-substituted 
-Mn1-xCrxO2 nanowires with nonaggregated morphology have been synthesized by the chemicaloxidation of layered LiMn0.9Cr0.1O2 microcrystals under hydrothermal conditions at elevated temperature.According to powder X-ray diffraction analysis, a persulfate treatment at 200 
C gives rise to a uniquetransformation from a monoclinic-layered structure to a pyrolusite- (-MnO2-) type structure. Electronmicroscopic analyses clearly demonstrated that the oxidized derivative consists of well-separated single-crystalline nanowires with a diameter of ~30 nm and a length of several micrometers. Mn K-edge and CrK-edge X-ray absorption spectroscopy and chemical analysis provide straightforward evidence for thesubstitution of chromium ions for the manganese sites of the pyrolusite-structured manganese oxide nanowires.Of special importance is that the present Cr-substituted -MnO2-type nanowires show promising electrodeperformance for Li+ ion batteries, superior to those of pristine LiMn0.9Cr0.1O2, bulk -MnO2, and other structure-type manganese oxide nanowires including unsubstituted -MnO2 nanowires. On the basis of the presentexperimental findings, we are able to conclude that the persulfate treatment under hydrothermal conditionsprovides a powerful method not only to prepare cation-substituted manganese oxide nanowires but also toimprove the electrode performance of microcrystalline metal oxides through nanostructure fabrication.
-Mn1-xCrxO2 nanowires with nonaggregated morphology have been synthesized by the chemicaloxidation of layered LiMn0.9Cr0.1O2 microcrystals under hydrothermal conditions at elevated temperature.According to powder X-ray diffraction analysis, a persulfate treatment at 200 C gives rise to a uniquetransformation from a monoclinic-layered structure to a pyrolusite- (-MnO2-) type structure. Electronmicroscopic analyses clearly demonstrated that the oxidized derivative consists of well-separated single-crystalline nanowires with a diameter of ~30 nm and a length of several micrometers. Mn K-edge and CrK-edge X-ray absorption spectroscopy and chemical analysis provide straightforward evidence for thesubstitution of chromium ions for the manganese sites of the pyrolusite-structured manganese oxide nanowires.Of special importance is that the present Cr-substituted -MnO2-type nanowires show promising electrodeperformance for Li+ ion batteries, superior to those of pristine LiMn0.9Cr0.1O2, bulk -MnO2, and other structure-type manganese oxide nanowires including unsubstituted -MnO2 nanowires. On the basis of the presentexperimental findings, we are able to conclude that the persulfate treatment under hydrothermal conditionsprovides a powerful method not only to prepare cation-substituted manganese oxide nanowires but also toimprove the electrode performance of microcrystalline metal oxides through nanostructure fabrication.