(701g) Pt Nanoparticles on Sb-SnO2 Is an Ultra-Stable, Active Oxygen Reduction Reaction (ORR) Catalyst
The commercial deployment of PEMFCs is hindered by the insufficient durability of commercial catalysts caused by the degradation of the catalysts supports. To increase the stability and activity of the catalyst, highly conductive and stable Sb-SnO2 (ATO) supports was synthesized by a xerogel method to replace the typical carbon supports found in the commercial state-of-the-art catalysts. To overcome the inadequate dispersion of Pt particles on the metal oxide support, a colloidal method was employed to achieve small Pt particle size and uniform particle dispersion. This method of catalyst deposition was compared with other wet chemical methods and the colloidal method was shown to result in catalysts with ultrahigh ECSA (68m2/g) and excellent catalytic activity for oxygen reduction reaction (ORR). Further, the effect of annealing conditions was also examined for these supports and its effects comprehensively characterized using TEM and XPS. Accelerated stability tests (ASTs) were performed for both Pt/C and Pt/ATO made with the various methods using the DOE/FCCJ protocol. After 10,000 accelerated start-stop cycles, Pt/ATO was found to retain 100% of its ECSA compared to Pt/C (57.6% retained) while showing Pt/C-like electrocatalytic activity. This ex-situ stability in combination with Pt/C like activity and performance in a fuel cell indicates that Pt/ATO is a very promising long-life catalyst for fuel cell application.