Ion limited charging of nanoparticle thin films

COLL 297

Bernadette M Quinn, Laboratory of Physical Chemistry and Electrochemistry, Helsinki University of Technology, P.O. Box 6100, Espoo, 02015 HUT, Finland, Virginia Ruiz, Department of Chemistry, University of Burgos, Pza. Misael Bañuelos, s/n, 09001 Burgos, Spain, and Timo Laaksonen, Division of Pharmaceutical Technology, University of Helsinki, P.O. Box 56, Helsinki, FI-00014, Finland.
The charging behavior of thin films of alkanethiol protected gold nanoparticles, so called monolayer protected clusters (MPCs), immersed in aqueous solution is discussed. We report how differences in ion solvation in the film vs. the electrolyte phase can control the apparent redox properties of such films. MPC charging at the electrode surface is not possible without the transfer of counter-ions across the film/solution interface to preserve the electroneutrality of the film.

The ion-transfer limited model developed is discussed and its predictions compared with experiment. Langmuir-Schaefer MPC thin films were transferred to a glassy-carbon electrode and film charging behavior investigated in a series of aqueous electrolytes of differing lipophilicities.

Our interpretation of the MPC film charging has important consequences for all devices based on hydrophobic redox active thin films immersed in hydrophilic media. Device response will depend on counter-ion transfer across the solution/film interface and must be taken into account.

 

Electrochemistry-Enabled Nano S&T
9:00 AM-11:55 AM, Tuesday, April 8, 2008 Morial Convention Center -- Rm. 226, Oral

Division of Colloid & Surface Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008