Studies of electrochemical behavior of SWNT-film electrodes

Abstract

The redox reactions of 4 mmol L-1 K4[Fe(CN) 6] species have been studied with Single-Walled Carbon Nanotube (SWNT)-coated Glassy Carbon Electrode (GCE), SWNT-coated Gold Electrode (GE) and lab-made SWNT-film (SWNT-Thin-Paper-Like-Film) Electrodes individually. The SWNT-modified (physically) electrode has shown a well-defined redox peak compared with bare electrodes. CV is used in 50.0 mmol L-1 KCl containing K4[Fe(CN)6] to obtain information on both the capacitive background and electron transfer from the faradaic reaction of the redox species. The capacitance gives insight into the effective surface area (including both the exterior surface and the interior surface within the SWNT-coated glassy carbon and gold electrodes and SWNT-film electrode) as well as the Pseudocapacitance due to faradaic reactions of surface bonded oxides. Among the three kinds of electrode, the SWNT-film electrode presented the largest volume specific capacitance, consistent with its highest carbon nanotube packing density and largest effective surface area. This indicates that the carbon nanotube-working electrode (whether coated or film electrode) behaves as a three-dimensional electrode. The redox reaction of Fe(CN)63-/Fe(CN)64- was found to occur not only at the outer surface of the carbon nanotube but also at the interior surface of the thin paper like nanotube electrode. ©2007 Sociedade Brasileira de Química.