Advanced fuel cell catalysts - Sulfonation of carbon-supported catalysts using 2-aminoethanesulfonic acid

To make carbon catalyst-support particles to possess both electronic and protonic conductivities, ethanesulfonic acid groups (-CH2CH2SO3H) were chemically linked onto their surface through a diazonium salt formed by reacting 2-aminoethanesulfonic acid with isobutyl nitrite. The resulting sulfonated carbon-supported catalyst became much more acidic than the untreated counterpart, and a thermal gravimetric analysis indicated that the optimal amount of ethanesulfonic acid groups was about 0.23 mmol onto each gram of 20% Pt/Vulcan XC-72. Fuel cell electrodes made using the sulfonated catalyst showed 60% higher performance than the untreated counterpart, while the optimal Nafion content within the catalyst layer was reduced by nearly half. (C) 2003 The Electrochemical Society.