Dramatically Enhanced Oxygen Fluxes in Fluorite-Rich Dual-Phase Membrane by Surface Modification

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• 作者：Jong Hoon Joo ; Kyong Sik Yun ; Younki Lee ; Jaewon Jung ; Chung-Yul Yoo ; Ji Haeng Yu
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：August 12, 2014
• 年：2014
• 卷：26
• 期：15
• 页码：4387-4394
• 全文大小：430K
• ISSN：1520-5002

文摘

Dual-phase ceramic membranes with very high oxygen flux have been designed by taking into account the volume fraction of the fluorite phase, membrane thickness, and surface modification. The oxygen flux of Ce_0.9Gd_0.1O_{2鈭捨?/sub>鈥揕a0.6Sr0.4Co0.2Fe0.8O3鈭捨?/sub> (GDC鈥揕SCF) dual-phase membranes has been systematically investigated as a function of membrane thickness and volume fraction of the fluorite phase with or without surface modification. The percolation threshold of the composites for electronic conduction has been determined to be about 20 vol % of LSCF by general effective-medium theory. The oxygen flux of uncoated fluorite phase-rich membrane (80 vol % GDC鈥?0 vol % LSCF) with 30-渭m thickness exhibits a low oxygen flux (8.0 脳 10^鈥? mL路cm^鈥?路min^鈥? at 850 掳C) under an air/He gradient, indicating that the permeation is controlled by only the surface-exchange kinetics of GDC. With both sides coated with La0.6Sr0.4CoO3鈭捨?/sub> (LSC), the flux of the membrane (3.6 mL路cm^鈥?路min^鈥? at 850 掳C) has been dramatically enhanced by about 3 orders of magnitude in comparison with the oxygen flux of the membrane with a nonmodified surface. This observation implies that surface modification has a decisive role in dramatically enhancing the contribution of the GDC to the fluorite rich dual-phase membrane.}