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Charge-transfer reactions at the liquid/liquid
interface probed by nanopipette voltammetry |
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A nanopipette is filled with an aqueous solution and immersed in an outer solution immiscible with water. By applying voltage between the reference electrode inside the pipette and the external reference, one can induce either ion transfer (A) or electron transfer (B) across the liquid/liquid interface. |
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Voltammogram of tetraethylammonium transfer from 1,2-dichloroethane to water at a 25-nm pipette electrode (symbols). Kinetics of ion transfer can be extracted from the best theoretical fit (solid line). |
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Generation/collection experiments with θ–pipettes. In a θ–pipette, two closely spaced coplanar pipette orifices are separated by a thin line of glass. Both generator and collector pipettes are filled with an aqueous solution and immersed in organic solution. When a generator pipette is biased positively with respect to an external reference, cations are transferred from it to the outer solution. Some of those ions diffuse to the orifice of the collector pipette (biased at a more negative potential) and transfer into it. The collection efficiency can be measured and used to study mechanisms of ionic reactions. |
