On the enhancement of methanol and CO electro-oxidation by amorphous (NiNb)PtSnRu alloys versus bifunctional PtRu and PtSn alloys

Abstract

Abstract It has been observed in this work and previous works [J. Barranco, A.R. Pierna, J. Non-Cryst. Solids 35 (2007) 851; J. Barranco, A.R. Pierna, J. Power Sources 169 (2007) 71 [1,2] ] that (NiNb) 99 (PtSn) 1 alloys surfaces are very effective catalyst for CO electro-oxidation, but not for methanol electro-oxidation. On the contrary, (NiNb) 99 (PtRu) 1 alloys seem to be a very effective catalyst for methanol, but not for CO, electro-oxidation. Since CO ads is postulated to be a by-product in methanol electro-oxidation on Pt alloy surfaces, the lack of inactivity of (NiNb) 99 (PtSn) 1 amorphous alloys appears paradoxical. In this work we present the behaviour of a tricatalytic amorphous alloy, in methanol and CO ads electro-oxidation in an attend to enhance the methanol and CO oxidation mechanisms of the Sn and Ru containing alloys, respectively. It has been observed that the specific activity for (NiNb) 99 (PtSnRu) 1 for methanol electro-oxidation, is enhanced around 50–80% with respect the bicatalytic PtSn alloys, at low methanol concentration, whereas PtRu catalysts seems to be more effective. At high methanol concentrations, (NiNb) 99 (PtSnRu) 1 catalysts seems to be more effective. The enhanced in the CO ads , is observed by the lower rate of poisoning of such alloy compare with the bicatalytic ones. The onset of CO ads oxidation, appear to shift 0.25 V towards negative values of potentials, with respect (NiNb) 99 (PtRu) 1 electrodes.