Influence of the Temperature for the Ethanol Oxidation Reaction (EOR) on Pt/C, Pt‐Rh/C and Pt‐Rh‐SnO₂/C

Abstract

Abstract The electrocatalytic activity of Pt/C, Pt‐Rh/C and Pt‐Rh‐SnO 2 /C electrocatalysts toward the ethanol oxidation reaction (EOR) was investigated in a three‐electrode assembly at 25 °C, 40 °C and 70 °C in acidic medium. The 10 wt.% electrocatalysts were prepared with a modified polyol method and physically characterized by both X‐Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The CO‐stripping study revealed that CO ad oxidation initiates at lower potential on Pt‐Rh/C and Pt‐Rh‐SnO 2 /C than on Pt/C and shifts negatively when the temperature increases. The positive effect of the temperature is maintained for the EOR: the three electrocatalysts exhibit a higher activity and a negative shift of the EOR wave at higher temperature. Pt‐Rh‐SnO 2 /C demonstrates the lowest EOR onset potential of the three electrocatalysts. The steady‐state Tafel slopes and apparent activation energies E a were determined in 0.5 M H 2 SO 4 + 0.1 M EtOH between E = 0.4 and 0.7 V vs. RHE in the temperature range 25–70 °C. The results show rather comparable rate determining steps ( rds ) for the ethanol electrooxidation on Pt/C and Pt‐Rh/C in the ranges of potential and temperature studied. The EOR on Pt‐Rh‐SnO 2 /C seems less influenced by the potential than on Pt/C and Pt‐Rh/C electrocatalysts, but is more temperature sensitive.