Electrochemistry and Fluid Flow in Confined Spaces
Negative Solution Resistance, a H2 Nanobubble, and Coulomb Transport
Electrochemical systems exhibit interesting and useful behaviors when investigated in highly confined spaces. In this seminar, three examples of new electrochemical phenomena that appear at the nanoscale will be presented. In the first example, a Pt nanodisk electrode is used to generate a single high-pressure (150 atm) 10-nm-radius H2 bubble in aqueous solution. The kinetics of H+ reduction are measured at the nanobubble/solution/Pt interface and used to obtain an estimate the width of a 3-phase boundary (~0.1 nm).
In the second example, negative differential resistance (NDR) is demonstrated in a glass membrane containing a single 100-nm radius nanopore filled with a KCl solution. NDR is shown to occur from a true voltage-dependent bistability in fluid flow within an electrically charged nanopore; applications of NDR in chemical sensing are presented. In the third example, high field transport of ions (“Coulomb transport”) between two closely spaced Au electrodes (50 nm) is shown to lead to non-classical i-V behavior that can enhance or inhibit the electrical power available from a thin-layer electrochemical cell.