Trimetallic catalyst based on PtRu modified by irreversible adsorption of Sb for direct ethanol fuel cells

In this work, PtRu/C-Sb materials prepared by adding a Sb salt to the ink of commercial PtRu/C were studied as catalysts for ethanol oxidation. The prepared trimetallic catalysts showed enhanced properties for ethanol oxidation trough a wide range of surface coverages. However, coverage higher than 0.7 of Sb on PtRu/C causes the decrease of the catalytic activity suggesting that specific sites composed by the 3 metals are necessary to achieve the highest performance. In situ Fourier Transformed Infrared Spectroscopy experiments were also performed to compare the reaction products of the bimetallic and trimetallic catalysts. The catalysts were also tested under fuel cell conditions. Also in this case, higher power densities, higher open circuit voltages and better stability than the bimetallic substrate were found. With this catalyst preparation method, the catalysts showed 2 times higher current densities than for the PtRu catalysts and 6 times better than for pure Pt anodes.Peer reviewe

Pt catalysts modified with Bi: Enhancement of the catalytic activity for alcohol oxidation in alkaline media

Recent developments on anion-exchange membranes for fuel cell application renewed the interest in the study of alcohol oxidation at high pHs for applications in anion-exchange membrane direct alcohol fuel cells (AEM-DAFC). Although platinum is still the most studied catalyst for oxidation of alcohols in alkaline media, the introduction of one or more metals in order to increase the oxophilicity of the catalyst is a common approach in the development of improved materials for these reactions. In this manuscript, we report the enhancement of the catalytic activity of Pt/C toward ethanol, methanol, and propanol oxidation in alkaline media by simple adsorption of Bi surface. The activity was checked by cyclic voltammetry, and the reaction products and intermediates were analyzed by “in situ” infrared spectroscopy. The presence of Bi was shown to increase the activity of Pt toward the oxidation of the referred alcohols by acting as a third body (impeding surface poisoning) and also by an electronic effect (on water adsorption at the surface).Financial support from Aalto University, MICINN (Feder) and Generalitat Valenciana through Projects CTQ2010-16271 and PROMETEO/2009/45