Synthesis and Evaluation of Low Platinum-Content Pt-CeO x /MWCNT Cathodes for the ORR in the Absence and Presence of Ethanol in Acid Media

We present in this work the electrochemical activity for the oxygen reduction reaction (ORR) of a 20% Pt-CeOx/MWCNT electrocatalyst with low-platinum content, synthesized by the microwave-assisted polyol method. The cathode shows a high mass specific catalytic activity in acid media as well as remarkable inertness in the presence of ethanol. EDAX analysis indicates that the weight percent content of platinum in the composite cathode was 3.9 wt %. Meanwhile, XPS characterization of ceria reveals a material with mixed Ce+3 and Ce+4 oxidation states, with a predominant Ce2O3 phase. The catalytic activity for the ORR and enhanced tolerance properties of Pt-CeOx/MWCNT to ethanol are ascribed to the presence of the Ce3+ state in the composite cathode.