Effect of platinum particle size on the performance of PAFC O2 reduction electrocatalysts

The influence of the electrocatalyst characteristics upon activity and stability for the oxygen reduction reaction in phosphoric acid fuel cell (PAFC) systems is widely established. The initial catalytic performance progressively decreases, even on a short-term basis, under operational conditions, due to several factors such as Pt dissolution, sintering and carbon corrosion. The performance of catalysts depends upon the morphological characteristics of the electrodes. The proper tailoring of the Pt/C catalyst plays a fundamental role in obtaining high overall performance in such electrochemical devices. A high mass activity (mA mg-1) and low voltage decay are found, in the present investigation, for catalysts having Pt surface area above 80 m2g-1. Such results have been tentatively interpreted in terms of the acid-base properties of the surface, as determined by a potentiometric titration technique.