Date of Award

1-1-2010

Document Type

Campus Access Thesis

Department

Chemical Engineering

First Advisor

Branko N. Popov

Abstract

The durability of cathode catalysts in proton exchange membrane fuel cells (PEMFCs) is perhaps the most critical issue that hinders the success of PEMFCs application. Specific durability requirements include resistance to corrosion of the catalyst support, stability of the electrochemical surface area against platinum dissolution, agglomeration, and poisoning, and a negligible peroxide/water production ratio.

In this study, a novel mesoporous SnO2 support was successfully prepared to take the place of conventional carbon supports because of its high oxidation resistance under PEM fuel cell operation conditions. Platinum nanoparticles (~5 nm) were deposited on the SnO2 support via a modified polyol method. The physical properties of the Pt/SnO2 catalyst were characterized by X-ray diffraction, BET surface area, and transmission electron microscopy. The electrochemical characterizations were performed with a rotating ring-disk electrode and cyclic voltammograms.

The durability and stability of the membrane electrode assembly with the Pt/SnO2 catalyst were measured under accelerated stress tests proposed by U.S. Department of Energy. The corrosion resistance of the catalyst support was investigated by holding the cell potential at 1.2 V for 200 h. The potential sweeping method (0.7-1.2 V) was applied to the investigation on platinum sintering effect. Both tests indicated that SnO2 is a promising support candidate for PEM fuel cells. These studies also demonstrated that Pt/SnO2 with high electrochemical activity and high tolerance to ECSA loss is more robust than a traditional Pt/C under PEM fuel cell operation.

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