On the limiting factor of impregnation methods for developing Cu/CeO2 anodes for solid oxide fuel cells
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The efficiency of impregnation methods for making Cu-based solid oxide fuel cells (SOFCs) is qualitatively characterized for the first time through a conformal coating model. It is found that the low-efficiency results from the uneven distribution of Cu instead of the small loading. Most of the Cu deposits form isolated islands, e.g., in a 20.4 vol.% Cu-loaded anode, 81% Cu is isolated from each other. In order to address the limited impregnation efficiency, two different procedures are adopted to fabricate the practical Cu/CeO2 anodes, namely, simultaneous and sequential impregnation procedures. It is found that CeO2 works as a solid dispersant, improving the Cu distribution drastically. Compared to the Cu-only anode, more than a threefold improvement of impregnation efficiency is achieved by both methods. The anode made by the sequential impregnation yields the best performance in CH4 at 700 °C, 170 mW cm−2, which represents an 18% enhancement over that of the simultaneous impregnation, or 340% over the Cu-only anode. These findings demonstrate that it is of importance to optimize the Cu impregnation to yield a highly active anode, and the sequential impregnation method is a promising procedure to break the efficiency-limiting factor and produce a high-performance anode with minimized fabrication effort.
KeywordsAqueous impregnation Cu-CeO2 anode Electrode performance Microstructure optimization Hydrocarbon solid oxide fuel cells
This research was supported by the Ministry of Science and Technology of China (2007AA05Z139) and by Natural Science Foundation of China (20901020, 51372057).
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