CO tolerance of PdPt/C and PdPtRu/C anodes for PEMFC

The performance of H2/O2 proton exchange membrane fuel cells (PEMFCs) fed with CO-contaminated hydrogen was investigated for anodes with PdPt/C and PdPtRu/C electrocatalysts. The physicochemical properties of the catalysts were characterized by energy dispersive X-ray (EDX) analyses, X-ray diffraction (XRD) and “in situ” X-ray absorption near edge structure (XANES). Experiments were conducted in electrochemical half and single cells by cyclic voltammetry (CV) and I–V polarization measurements, while DEMS was employed to verify the formation of CO2 at the PEMFC anode outlet. A quite high performance was achieved for the PEMFC fed with H2 + 100 ppm CO with the PdPt/C and PdPtRu/C anodes containing 0.4 mg metal cm−2, with the cell presenting potential losses below 200 mV at 1 A cm−2, with respect to the system fed with pure H2. For the PdPt/C catalysts no CO2 formation was seen at the PEMFC anode outlet, indicating that the CO tolerance is improved due to the existence of more free surface sites for H2 electrooxidation, probably due to a lower Pd–CO interaction compared to pure Pd or Pt. For PdPtRu/C the CO tolerance may also have a contribution from the bifunctional mechanism, as shown by the presence of CO2 in the PEMFC anode outlet.