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Conical nanopores fabricated via a pressure-biased chemical etch

RSC Advances

Small, Leo J.; Wheeler, David R.; Spoerke, Erik D.

Controlling the size and shape of nanopores in polymer membranes can significantly impact transport of molecular or ionic species through these membranes. Here we describe a facile method to controllably form conical nanopores in ion-tracked polycarbonate membranes. Commercial polycarbonate ion-tracked membranes were placed between a concentrated alkaline solution and an acidic solution. By varying the height of the acidic solution, the hydrostatic pressure was controlled, regulating the acid flux through the nanopores. The resulting asymmetric etching of the membrane produced conical pores with controllable aspect ratios. Scanning electron microscopy of both the pores and nickel nanostructures electrolessly templated in the pores confirms their conical shape. This safe, straightforward approach obviates the need to use large voltages, currents, and/or plasma etching equipment traditionally employed to create conical nanopores. © 2014 The Royal Society of Chemistry.

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Influence of analysis method on the experimentally observed capacitance at the gold-ionic liquid interface

Journal of the Electrochemical Society

Small, Leo J.; Wheeler, David R.

Diverse results have been reported on the differential capacitance of the metal-ionic liquid interface. Here the effect of the analysis method on the experimentally observed double layer capacitance is evaluated. A fast Fourier transform impedance spectroscopy technique allows the impedance-DC bias landscape of three 1-alkyl-3-methylimidazolium salts to be explored over a wide range of frequencies in a fraction of the time required for traditional impedance techniques. Analysis of this data set using four different methods found in the literature demonstrates how the assumptions inherent to each method alter the capacitance-DC bias curve. Careful consideration of these assumptions is necessary to compare results across the literature and understand the properties inherent to the solid-ionic liquid interface.

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Results 201–215 of 215
Results 201–215 of 215