Electrochemical Behavior of SWCNT-TPLF Electrode Compared to SWCNT-coated GCE and GE Electrodes

Redox reaction [Fe(CN)6] 3– / [Fe(CN)6] 4– has been studied with a Single-Walled Carbon Nanotube (SWCNT)-coated Glassy Carbon Electrode (GCE), SWCNT-coated Gold Electrode (GE) and a lab-made SWCNT-TPLF (SWCNT-Thin-Paper-Like-Film) Electrode. The SWCNT-modified electrode has shown a well-defined redox peak compared to bare electrodes. Cyclic voltammetry was used in 50.0 × 10–3 M aqueous solution of 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 and interior surfaces within the coated and TPLF electrodes) as well as the pseudocapacitance due to faradaic reactions of surface bonded oxides. Among the three types of electrodes, the SWCNT-TPLF electrode showed 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)6] 3– / [Fe(CN)6] 4– 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.