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

Abstract

When a current or a voltage is applied across the ceramic membrane of the nongassing Ag/Ag(2)O-SiO(2)-Ag/Ag(2)O pump, protons produced in the anodic reaction 2Ag(s) + H(2)O → Ag(2)O(s) + 2H(+) + 2e(-) are driven to the cathode, where they are consumed by the reaction Ag(2)O(s) + H(2)O + 2e(-) → 2Ag(s) + 2 OH(-). The flow of water is induced by momentum transfer from the electric field-driven proton-sheet at the surface of the ceramic membrane. About 10(4) 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 Ag(2)O decrease the flow. Their accumulation is reduced by applying Nafion-films to the electrodes. The 20 μL min(-1) 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.

Development of Redox-Conducting Polymer Electrodes for Non-Gassing Electro-Osmotic Pumps: A Novel Approach

“…7 The development of non-gassing electrode materials for EOPs is the focus of our research group. [8][9][10][11] The use of non-gassing electrode materials in EOPs was initially demonstrated by Luft, Kuhl, and Richter in 1977. [12][13][14] Later, others [12][13][14] used Ag/AgCl electrodes, wherein consumable silver acted as an anode and AgCl as a cathode.…”

“…The use of the redox polymer, poly (3,4-ethylenedioxythiophene), as an electrode material has been previously reported. 15 In our earlier study [8][9][10][11] we described the most efficient non-gassing EOPs employing a Ag/Ag 2 O electrode, wherein Ag was electro-oxidized to Ag 2 O at the anode while the protons thus generated drifted to the cathode. However, at the cathode, Ag 2 O was electro-reduced to Ag, with net generation of water molecules.…”

Merging Electric Bacteria with Paper

“…The Ag 2 O solid‐state cathode has a very high standard potential E ° of +1.17 V (Equation ) close to that of oxygen (+1.229 V, Equation ), while it minimizes issues of the air‐cathode including low reactant collision probability and low aqueous oxygen solubility . The electrons and protons generated by the bacterial respiration move to the cathode reducing Ag 2 O to Ag.…”

Electrodeposition of Mn-Ni Oxide/PEDOT and Mn-Ni-Ru Oxide/PEDOT Films on Carbon Paper for Electro-osmotic Pump Electrode

“…However, because of the use of an additional device, the size of all equipment required including the EOP itself becomes inevitably large. To solve these problems caused through the use of a Pt electrode, we focused on the reactions occurring in the electrode and reported an EOP using electrodes of Ag/Ag 2 O and PANI-PSS [1]. An EOP using the above materials as an electrode does not generate any gas owing to the electrolysis of water and can be powered by a battery because it can be driven at a low voltage.…”