A Stable Ag/Ceramic-Membrane/Ag2O Electroosmotic Pump Built with a Mesoporous Phosphosilicate-on-Silica Frit Membrane

초록

Low-voltage non-gassing electro-osmotic pumps were built of phosphorylated silica frit membranes, formed meso-porous silica particles of 0.7-1.0 mu m diameter, sandwiched between porous, consumable, Nafion-coated Ag/Ag2O electrodes. The flow rates of pumps with membranes formed of the meso-porous silica particles were stable, remaining constant within +/- 12% until >= 80% of the 2.6 coulomb capacity of the Ag or Ag2O electrodes, sufficient for pumping about 5 mL water, was exhausted. The cause of the decay of the flow in these pumps is Ag+-accumulation at the non-mesoporous membrane surface, observed by metallic silver precipitation caused blackening of the light-exposed non-mesoporous membranes. When the membranes were made with the mesoporous particles, there was no silver precipitate on the membrane; instead, all of the silver was electrodeposited at the cathode. The stability of the flow of pumps made with meso-porous silica membranes is thus attributed to the rapid transport of Ag+-transport to the cathode. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.059201jes].

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