Double-Layer Controlled Responses at Nanodisk Electrodes and Nanopores.

YUE ZHAO, GRACIELA A. GONZALEZ, ANDREAS BUND, GANGLI WANG AND HENRY S. WHITE

Playa del Carmen

Conferencia; Electrochemistry Zing Conference; 2009

Zing Conference

Presentación oral: This presentation will describe experimental and numerical investigations of the electrical double layer control response of metal nanodisk electrodes (<100 nm radius), recessed nanodisk electrodes, and nanopores.  We show that electrical charge, immobilized on the surface of the insulating material used to prepare inlaid nanodisk electrodes and the walls of conical nanopores, has a surprisingly large effect on transport rates.  In one example, the interior surface of a nanopore electrode was modified with spiropyran moieties to impart photochemical control of molecular transport through the pore orifice (15-90 nm radius). In low ionic strength acetonitrile solutions, diffusion of a positively charged species (Fe(bpy)32+) is electrostatically blocked with 100% efficiency by UV light-induced conversion of the neutral surface-bound spiropyran to its protonated merocyanine form (MEH+). Transport through the pore orifice is restored by either irradiation of the electrode with visible light to convert MEH+ back to spiropyran or addition of a sufficient quantity of supporting electrolyte to screen the electrostatic field associated with MEH+. Finite-element numerical simulations to obtain solutions to the Poisson, Nernst-Planck, and Navier-Stokes equations yield accurate predictions of nanopore fluxes and the transport limited current at nanodisk electrodes.