Kinetics of electron transfer at Pt nanostructured film electrodes

The kinetics of electron transfer to nanoparticulate platinum/octyldiisocyanide films has been investigated. The films were grown by attachment of 1,8-diisocyanooctane onto gold, and Pt layers were constructed by contacting this film with a toluene solution of Pt nanoparticles. Repeating this procedure gave multilayer films. The rate of electron exchange between these and the hexacyanoferrate redox couple was investigated using three different techniques: cyclic voltammetry, rotating disk electrode, and ac impedance. For isocyanide-terminated films, incomplete coverage by the ligand resulted in a behavior similar to that of a partially blocked electrode. Good electronic communication throughout the film was apparent when the surface contained attached Pt nanoparticles. The measured rate constant decreased with increasing number of layers, and this effect has been ascribed to a reduced number of active sites where electron transfer can take place. The self-assembly method used is of interest for the self-organization of transition metal nanoparticles at electrode surfaces.