Electrochemical studies of thiol self-assembled monolayers at a heated gold-wire microelectrode

Mercaptoundecanoic acid (MUA) and glutathione (GSH) self-assembled monolayers were prepared on gold-wire microelectrode. Cyclic voltammetry was used to investigate the influence of temperature on electrochemical behaviors of Fe(CN)(6)(3-/4-) and Ru(NH3)(6)(3+/2+) at these SAMs modified electrodes in aqueous solution. It is found that temperature shows great influence on electron transfer (ET) and mass transport (MT) for the two SAMs modified electrodes and the influence of temperature depends on the charge properties of the redox couples and terminal groups of SAMs and the structure of the monolayer on gold surface. The temperature can greatly increase MT rate of Fe(CN)(6)(3-/4-) at both MUA and GSH modified electrodes. However, the increased NIT rate doesn't have any effect on the CV's for Fe(CN)(6)(3-/4-)/MUA system. For Ru(NH3)(6)(3+/2+), temperature can greatly improve the electrochemical reaction in both MUA and GSH modified electrodes, which is ascribed to temperature-induced diffusion and convection and the electrostatic interaction between Ru(NH3)(6)(3+/2+) and negatively charged carboxyl groups on the electrode surface.