Scanning Electrochemical Microscopy with Gold Nanotips: The Effect of Electrode Material on Electron Transfer Rates

The disk-type, polished Au nanoelectrodes were prepared, characterized, and used as tips in the scanning electrochemical microscope (SECM). Kinetic parameters were measured for several rapid heterogeneous electron transfer (ET) reactions and compared to those obtained previously at Pt nanoelectrodes. The kinetics of most investigated ET processes were found to be independent of the electrode material. In contrast to the previously reported results, the rate constant of hexaammineruthenium(III) reduction was somewhat higher at Pt than at Au electrodes in different electrolyte solutions. This finding suggests that this reaction exhibits some degree of nonadiabaticity.