Synthesis of the ceramic-metal catalysts (PtRuNi-TiO2) by the combustion method

Electrocatalysis on the anode side of PEM fuel cells (PEMFC) has been widely studied, however, little information has been published on cermet catalysts, probably due to the very low or negligible power density registered when a ceramic oxide is blended with Pt based powders. In spite of, this, there exists an advantage in the use of oxides, such as TiO2. This type of oxide can exhibit a bifunctional catalytical effect, as a Pt protecting matrix in the hydrogen oxidation reaction (H.O.R.) which increases CO oxidation and also promotes hydroxide formation, thus improving the oxidation of hydrogen. In this work, a trimetallic composition of 50 mol% (Pt-Ru-Ni, 60:30:10)-.50 mol% TiO2 is investigated as anode catalyst for a PEMFC. For the preparation of this catalyst, combustion synthesis was the route selected, which allows us to achieve a powder composite with trimetallic (PtRuNi) and ceramic (TiO2) phases. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and polarisation curves (after MEA construction) are used to evaluate the catalytic activity of this type of powder. The catalyst obtained shows a single trimetallic phase with an average particle size of 8 nm. The TiO2 was found mainly as anatase phase with an average particle size of 2-3 nm. No reaction was detected between the two phases. The high power density exhibited (107 mW cm(-2)) with this cermet may be attributable to by a bifunctional effect on the CO and hydrogen oxidation reactions which occur during the single cell operation. (c) 2007 Elsevier B.V. All rights reserved.