Enhancing ethanol oxidation rate at PtRu electro-catalysts using metal-oxide additives

Metal oxides are investigated, as additives of a PtRu/C catalyst, for enhancing the electro-oxidation of
ethanol in acidic solution. High surface area TiO2 and SnO2 additives are synthesized and physico-
chemically characterized. These oxides are added to PtRu/C during the catalytic ink preparation to obtain
tri-metallic composite electrodes. These composite electro-catalysts are investigated for the ethanol
electro-oxidation in half-cell configuration in comparison with additive-free PtRu/C and Pt/C catalysts.
The PtRu-based composite catalyst containing SnO2 promoter shows a lower onset potential and larger
current density for ethanol oxidation than the additive-free catalyst and that containing TiO2 promoter.
The composite catalysts (PtRu/C + metal oxide) are also used in a direct ethanol fuel cell under practical
operating conditions and assessed against the benchmark PtRu catalyst. An increase in performance is
recorded with the composite tri-metallic electrodes. The analysis of electro-catalytic activity towards
ethanol oxidation reaction and ethanolic residues coverage indicates an enhanced capability to activate
ethanol chemisorption or a larger electroactive surface area, together with a faster intrinsic activity at
lower overpotential, as the reasons for the improved performance with the use of metal oxide additives.