Carbon paper supported Pt/Au catalysts prepared via Cu underpotential deposition-redox replacement and investigation of their electrocatalytic activity for methanol oxidation and oxygen reduction reactions

Through a simple and rapid method, carbon papers (CPs) were coated with Au and the resulting Au/CP substrates were used for the preparation of Pt/Au/CP by Cu underpotential deposition (Cu UPD) and redox replacement technique. A series of Pt-n/Au/CP catalysts (where n = number of UPD-redox replacement cycles) were synthesized and their electrochemical properties for methanol oxidation reaction (MOR), and oxygen reduction reaction (ORR) were investigated by electrochemical measurements. The Pt-n/Au/CP electrodes show higher electrocatalytic activity and enhanced poison tolerance for the MOR as compared to a commercial Pt/C on CP (Pt/C/CP). The highest mass specific activity and Pt utilization efficiency for MOR was observed on Pt-1/Au/CP with a thickness close to a monatomic Pt layer. Chronoamperometric tests in methanol solution revealed that Pt-n/Au/CPs have much higher CO tolerance compared to Pt/C/CP. Among the Pt-n/Au/CPs, CO tolerance decreases with increasing the amount of deposited Pt, indicating that the exposed Au atoms in close proximity to Pt plays a positive role against CO poisoning. Compared with the Pt/C/CP, all the Pt-n/Au/CP electrodes show more positive onset potentials and lower overpotentials for ORR. For instance, the onset potential of ORR is 150 mV more positive and the overpotential is similar to 140 mV lower on Pt-4/Au/CP with respect to Pt/C/CP. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.