Chemical modification of proton exchange membrane fuel cell catalysts witha sulfonated silane

The surface modification of carbon supported Pt fuel cell catalysts by atta chment of a sulfonated silane is reported. Attachment of the silane to the carbon surface before Pt deposition yields higher performances than attachm ent after Pt deposition. Optimum performances for both types of modified ca talyst were reached at a 10% Nafion loading in the fuel cell catalyst layer , and were significantly better than that for an untreated standard catalys t at 10% Nafion loading. However, the optimum performance of the untreated catalyst, at 30% Nafion loading, was slightly better than that of the best treated catalyst. These results are explained by the fact that both optimiz ed catalyst layers contained approximately the same concentration of sulfon ate groups. (C) 2001 The Electrochemical Society. All rights reserved.