Some More Observations on the Unique Electrochemical Properties of Electrode-Monolayer-Nanoparticle Constructs

Physical and electrochemical properties of gold nanoparticle-based electrodes are highlighted. Polycrystalline gold electrodes are passivated by a self-assembled,monolayer, then the immobilization of gold nanoparticles switch on the electrochemical reactivity of ruthenium. Herein, gap-mode Raman studies show that the location of the nanoparticles is on the top of the monolayer, meaning that the switching on cannot be attributed to a direct electrical contact between nanoparticles and the gold support. This switching on feature is also not affected by the size of the gold nanoparticles with a range of diameters between 4 and 67 nm. Further, the charge of the nanoparticles is investigated by grafting chemical groups onto the nanoparticles which is observed to alter the electron-transfer kinetics. The variation in rate constant however is insufficient to attribute the switching on phenomenon to a possible adsorption of the redox species onto the nanoparticles.