Development of a highly stable Pt-based ORR catalyst over Mn-modified polyaniline-based carbon nanofibers

Abstract

The corrosion of carbon support is one of the key factors causing the deactivation of Pt-based oxygen reduction reaction (ORR) catalysts for proton exchange membrane fuel cells. In this work, a highly stable carbon support with a high graphitization degree, small diameter, and large surface area (polyaniline-based carbon nanofibers, CNF-1300-0.28Mn) was developed by condensation polymerization of aniline, followed by catalytic graphitization by Mn. A Pt-based ORR catalyst (Pt/CNF-1300-0.28Mn) was prepared by the ethylene glycol reduction method over polyaniline-based carbon nanofibers. ORR tests showed that Pt/CNF-1300-0.28Mn exhibited much higher activity and stability than the commercial JM-Pt/C catalyst. The half-wave potential of Pt/CNF-1300-0.28Mn exhibited a positive shift of 17 mV relative to that of JM-Pt/C. The mass activity and specific activity were 1.71 and 2.24 times higher than those of commercial Pt/C. After 5 K CV cycles from 1.0 to 1.5 V, the half-wave potential of Pt/CNF-1300-0.28Mn decreased by only 7 mV, much lower than that of JM-Pt/C (16 mV), indicating the excellent corrosion resistance property of the new support. After 20 K CV cycles from 0.60 to 0.95 V, the Pt/CNF-1300-0.28Mn also showed much higher durability than the commercial catalyst.