Insights on the SO2 Poisoning of Pt3Co/VC and Pt/VC Fuel Cell Catalysts

摘要

SO2 poisoning of carbon-supported Pt3Co (Pt3Co/VC) catalyst is performed at the cathode of proton exchange membrane fuel cells(PEMFCs)in order to link previously reported results at the elec- trode/solution interface to the FC environment. First, the surface area of Pt3Co/VC catalyst is rigorously characterized by hydrogen adsorption,CO stripping voltammetry and under potential deposition(upd) of copper adatoms.Then the performance of PEMFC cathodes employing 30wt.%Pt3Co/VC and 50wt.%Pt/VC catalysts is compared after exposure to 1ppmSO2 in air for 3 h at constant cell voltage of 0.6V.In agreement with results reported for the electrode/solution interface, thePt3Co/VC is more susceptive to SO2 poisoning than Pt/VC at a given platinum loading. Both catalysts can be recovered from adsorbed sulfur species by running successive polarization curves in air or cyclic voltammetry (CV)in inert atmosphere.However,the activity of Pt3Co/VC having 8764;3 times higher sulfur coverage is recovered more easily than Pt/VC.To understand the difference between the two catalysts in terms of activity recovery, platinum/sulfur interaction is probed by thermal programmed desorption at the catalyst/inert gas interface and CV at the electrode/solution interface and in the FC environment.