Novel CO tolerant anode catalysts for PEFC based on platinum and organic metal complexes

Polymer electrolyte fuel cells (PEFCs) are used as cogeneration power sources in residential power applications. However, carbon monoxide (CO) usually poisons the platinum (Pt) electrode catalyst during operation. Pt-Ru alloy catalysts are used to address poisoning, but their high cost poses a significant challenge for commercial applications. This paper presented details of a novel CO-tolerant catalyst based on organic metal complexes. The complexes were used as co-catalysts with Pt and had acrylic structures with 3 to 4 nitrogen ligands and 2 oxygen and 2 nitrogen ligands. The molecular structural dependence of the catalytic activity was tested in this experiment, as well as the central metal dependence of the complex. Organic metal complexes were prepared by mixing equi-molar amounts of metal acetate salt and organic ligands in ethanol in a nitrogen atmosphere. Mixed catalysts were prepared from the Pt precursor, platinum tetraammine chloride and the organic metal complexes. CO tolerance tests were performed with a potentiostat in a half-cell consisting of a half-MEA mounted in a Teflon holder. Catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Results of the study showed reduced CO poisoning of the Pt electrode catalyst during operation. It was concluded that the method may lead to renewed interest in PEFC commercial and residential applications. 3 refs., 2 figs.