Stability of Ultra-low Pt Anodes for Polymer Electrolyte Fuel Cells Prepared by Magnetron Sputtering

摘要

Anodes for polymer electrolyte fuel cells (PEFC) with ultra-low platinum loadings (3, 15 and 25 μgPt/cm2) were prepared by sputter deposition of platinum onto carbon cloth covered with a microporous carbon layer. Platinum nanoparticles as well as agglomerates were observed by TEM for all investigated Pt loadings. Sputtered anodes with Pt loadings of 15 and 25 μgPt/cm2 can be operated at currents up to 2 A/cm2 without voltage losses compared with a commercial anode with 500 μgPt/cm2. Anode loadings of 3 μgPt/cm2 yield a similar PEFC performance only at low current densities (0.5 A/cm2). Longevity tests at constant current density (0.5 A/cm2) show nearly constant cell voltages for up to 1,000 h for an anode loading of 25 μgPt/cm2. Lower Pt loadings (3 and 15 μgPt/cm2) lead to more distinct voltage losses, probably caused by CO traces in the hydrogen reactant gas. The CO poisoning is in part reversible by (electro)chemical oxidation of CO.