Nafion-Coating of the Electrodes Improves the Flow-Stability of the Ag/SiO2/Ag2O Electroosmotic Pump

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• 作者：Woonsup Shin ; Enhua Zhu ; Rajaram Krishna Nagarale ; Chang Hwan Kim ; Jong Myung Lee ; Samuel Jaeho Shin ; Adam Heller
• 刊名：Analytical Chemistry
• 出版年：2011
• 出版时间：June 15, 2011
• 年：2011
• 卷：83
• 期：12
• 页码：5023-5025
• 全文大小：694K
• 年卷期：v.83,no.12(June 15, 2011)
• ISSN：1520-6882

文摘

When a current or a voltage is applied across the ceramic membrane of the nongassing Ag/Ag₂O-SiO₂-Ag/Ag₂O pump, protons produced in the anodic reaction 2Ag(s) + H₂O 鈫?Ag₂O(s) + 2H⁺ + 2e^{鈥?/sup> are driven to the cathode, where they are consumed by the reaction Ag₂O(s) + H₂O + 2e鈥?/sup> 鈫?2Ag(s) + 2 OH鈥?/sup>. The flow of water is induced by momentum transfer from the electric field-driven proton-sheet at the surface of the ceramic membrane. About 104 water molecules flowed per reacted electron. Because dissolved ions decrease the field at the membrane surface, the flow decreases upon increasing the ionic strength. For this reason Ag+ ions introduced through the anodic reaction and by dissolution of Ag₂O decrease the flow. Their accumulation is reduced by applying Nafion-films to the electrodes. The 20 渭L min鈥? flow rate of 6 mm i.d. pumps with Nafion coated electrodes operate daily for 5 min at 1 V for 1 month, for 70 h when the pump is pulsed for 30 s every 30 min, and for 2 h when operating continuously.}