Determination of heterogeneous electron transfer rate constants at microfabricated iridium electrodes

There has been an increasing use of both solid metal and microfabricated ir idium electrodes as substrates for various types of electroanalysis. Howeve r, investigations to determine heterogeneous electron transfer rate constan ts on iridium, especially at an electron beam evaporated or de magnetron sp uttered surface, have not previously been performed. This paper compares th e results of these microfabricated surfaces using ultramicroelectrode array s and steady-state currents. Even though the de magnetron sputtered iridium surface demonstrated a slightly more reversible electrochemical behavior t han the electron beam evaporated surface, overall the microfabricated micro electrodes and ring electrode indicated similar reversibility to the polish ed metallic iridium disk electrode. (C) 1999 Elsevier Science S.A. All righ ts reserved.