Adsorption characteristics of Fe(CN)(3)(-/4)(6) on Au colloids as monolayer films on cysteamine-modified gold electrode

Self-assembled monolayers (SAMs) of chemisorbed cysteamine on gold electrod e surfaces have been used as base interfaces for the deposition of the An c olloid. Different Au colloids, ranging in particles of diameter 2.6, 16, 42 and 51 nm, can be deposited on self-assembled cysteamine monolayers on a g old electrode. Fe(CN)(6)(4-) adsorbed on Au colloid surfaces yields a pair of symmetric adsorption peaks with half-peak width (W-1/2) of 90.2 mV and p eak-to-peak separation (Delta E-p) of 3 mV in 1.0 M KNO3 solution containin g 1.00 x 10(-3) M K3Fe(CN)(6). The dependence of peak current on scan rate (nu) is linear. Delta E-p of the adsorption wave increases while the Au col loid size decreases. The apparent specific capacitances of a bare gold elec trode, the cysteamine-modified electrode and the Au colloid modified electr ode measured by cyclic voltammetry at 500 mV are 57.8, 32.0 and 81.1 mu F c m(-2), respectively. (C) 1999 Elsevier Science S.A. All rights reserved.