Advantageous combination of solid carbon paste and a conducting polymer film as a support of platinum electrocatalyst for methanol fuel cell

Electrodeposition of platinum is comparatively performed on four carbon-based supports: bare glassy carbon electrode (GCE), bare solid carbon paste electrode (sCPE), and a conducting polymer film coated GCE and sCPE. Both the sCPE and poly(2-amino-5-mercapto-1,3,4-thiadiazole) (PAMT) are first used to deposit Pt, with an aim of improving electrocatalytic activity of Pt toward methanol oxidation. Scanning electron microscopy shows that chestnut bur-like Pt particles with numerous nanothorns are deposited on all the supports by controlling deposition potential and time, and the particles on the PAMT film supported on the both substrates are found in two size fractions (<1 mu m and 2-3 mu m). Voltammetric data indicate that both the sCPE and the PAMT contribute to increase electrochemical active area of Pt catalyst and therefore have a positive effect on Pt's electrocatalytic activity, in comparison with the GCE and the uncoated supports, respectively. Moreover, impedance spectroscopy reveals that the sCPE-supported PAMT facilitates the electron transfer kinetics of methanol oxidation, whereas the GCE-supported PAMT gives an opposite effect on the electron transfer. This work shows that the solid carbon paste is superior to glassy carbon for use in combination with a conducting polymer as a support of Pt electrocatalyst. (C) 2012 Elsevier B.V. All rights reserved.