Pt and PtRu electrocatalysts supported on carbon xerogels for direct methanol fuel cells

Carbon xerogels (CXs) have been prepared by polycondensation of resorcinol and formaldehyde in water by the sol-gel method. Functionalization with diluted and concentrated nitric acid as oxidizing agents was carried out to create surface oxygen groups, acting as anchoring sites for metallic particles. Characterization techniques included nitrogen physisorption, scanning electron microscopy, temperature programmed desorption and temperature programmed oxidation. Functionalized xerogels were used as supports to synthesize Pt and PtRu electrocatalysts by a conventional impregnation method. Catalysts electrochemical activity towards the oxidation of methanol was studied by cyclic voltammetry and chronoamperometry to establish the effect of the surface chemistry on the catalysts synthesis. Carbon monoxide oxidation was also studied to determine the electrochemical active area and the CO tolerance of the as prepared catalysts. Results were compared to those obtained with commercial Pt/C and PtRu/C catalysts supported on Vulcan XC-72R (E-TEK). All electrocatalysts supported on carbon xerogel showed better performances than commercial ones, providing higher current density values for the oxidation of methanol. (C) 2010 Elsevier B.V. All rights reserved.