Pt-Ru Supported on Carbon Xerogels as Electrocatalysts for Direct Methanol Fuel Cells

摘要

In the present work carbon xerogels were prepared by poly condensation of resorcinol and formaldehyde in water by the sol-gel method, to be used as support for PtRu catalysts. These xerogels were functionalized with different oxidizing agents to create surface oxygen groups that act as anchoring sites for metallic particles. The oxidizing agents employed were diluted HNO_3 and concentrated HNO_3 at room temperature for 0.5 and 2 h. Functionalized xerogels were characterized by nitrogen physisorption, temperature programmed desorption (TPD) and temperature programmed oxidation (TPO) prior its use as catalysts supports. Pt and Ru were deposited onto the former by the sodium borohydride method. Then, catalysts so obtained were characterized by cyclic voltammetry and chronoamperometry to study their activity towards methanol oxidation. Results with these materials were compared with a commercial catalyst, Pt-Ru/ETEK. Catalysts supported onto carbon xerogels presented better catalytic performances towards the oxidation of methanol than the commercial PtRu_ETEK, appearing like a good alternative for traditional carbon black supports.