EFFECT OF PLATINUM PARTICLE-SIZE ON THE PERFORMANCE OF PAFC O-2 REDUCTION ELECTROCATALYSTS

The influence of the electrocatalyst characteristics upon activity and stability for the oxygen reduction reaction in phosphoric acid fuel c ell (PAFC) systems is widely established. The initial catalytic perfor mance progressively decreases, even on a short-term basis, under opera tional conditions, due to several factors such as Pt dissolution, sint ering and carbon corrosion. The performance of catalysts depends upon the morphological characteristics of the electrodes. The proper tailor ing of the Pt/C catalyst plays a fundamental role in obtaining high ov erall performance in such electrochemical devices. A high mass activit y (mA mg(-1)) and low voltage decay are found, in the present investig ation, for catalysts having Pt surface area above 80 m(2) g(-1). Such results have been tentatively interpreted in terms of the acid-base pr operties of the surface, as determined by a potentiometric titration t echnique.