Enhancing PEM fuel cell performance by introducing additional thin layers to sputter-deposited Pt catalysts

Polymer electrolyte membrane (PEM) fuel cells with sputter-deposited Pt catalyst thin films and different sublayers added before the deposition of the Pt films to enhance the fuel cell performance are presented. Comparison of the performance of the fuel cells shows, for example, that thin films of Cr or silicone-like layers enhance the performance of the prepared cells of 15 mm x 15 mm electrode area. The achieved peak power density at room temperature and ambient pressure for a H-2/O-2 operated fuel cell loaded with 0.054 mg cm(-2) (25 nm) Pt per electrode was 210 mW cm(-2). Addition of a thin layer of Cr (I nm) underneath the catalyst layer (0.054 mg cm-2 Pt) improved the maximum power density to 259 mW cm-2. Scanning electron microscopy analysis showed that this is due to the change in morphology of the growth of the Pt catalyst layer on the Cr seeds. The performance of fuel cells prepared for reference from commercially catalyzed electrodes with standard carbon-supported Pt loadings of 0.5 and 1 mg cm(-2) could be improved after treatment of the electrodes in an oxygen plasma. The physically assisted removal of carbon and CF-groups from the surface in the oxygen plasma most likely uncovers more Pt sites from the carbon-supported Pt catalyst. (C) 2007 Elsevier B.V. All rights reserved.