Product distribution and the reaction kinetics at the anode of direct ethanol fuel cell with Pt/C, PtRu/C and PtRuRh/C

Product distribution at the anode of the direct ethanol fuel cell (DEFC) with different catalysts, i.e., Pt/C, PtRu/C and PtRuRh/C, at 353 K was investigated, and the effect of Rh addition to the PtRu and Ru addition to the Pt on the anode reaction were discussed based on a simple two-step reaction model. It was confirmed that the DEFC with the PtRuRh(2:1:1)/C catalyst showed the highest power density in the DEFCs with the prepared catalysts including Pt/C, PtRu(1:1)/C, PtRuRh(2:1:1)/C and PtRuRh(1:1:2)/C. The Ru and Rh additions increased the current density of the DEFC; however, they reduced the selectivity for CO2. Based on the calculated rate constants, it was revealed that the Ru addition increased both the rates of ethanol to acetaldehyde and acetaldehyde to acetic acid, and these rates were further increased by the Rh addition. On the other hand, Ru and Rh additions decreased the rate constant of acetaldehyde to CO2.

► Comparison among PtRuRh/C, PtRu/C and Pt/C catalysts for ethanol electro-oxidation.
► Product distribution at the anode of DEFC with the different catalysts.
► Rh addition to PtRu increased the current density but decreased the CO2 selectivity.
► A simple two-step reaction model for the ethanol electro-oxidation.