Comparison of Pt-Doped Membranes for Gas Crossover Suppression in Polymer Electrolyte Water Electrolysis
S. Garbe, Erik Samulesson, Thomas J. Schmidt, Lorenz Gubler
Abstract
A key concern for the safe operation of polymer electrolyte water electrolysis (PEWE) cells is the high hydrogen gas crossover that can lead to explosive hydrogen-oxygen gas mixtures. The safety aspect is especially important with thin membranes, high differential pressures and low current densities. Pt particles incorporated into the membrane catalyze the recombination of H 2 and O 2 to water and lower the content of hydrogen in the oxygen product stream. So far, different approaches have been taken for Pt distribution over the membrane's cross-section to suppress the hydrogen gas crossover: interlayer distribution, border distribution and uniform distribution. This work reports that only border-distributed Pt and uniformly-distributed Pt allow PEWE operation over a satisfying current density range for an extrapolated cathodic pressure of 30 bar a . Uniform Pt reduction allows a 50% larger operational range than Pt deposition at the border. Further, it is found that reduction of the Pt content in the membrane from 0.06 to 0.01 mg cm -2 does not allow satisfactory gas crossover suppression.