Comparison of Pt-Doped Membranes for Gas Crossover Suppression in Polymer Electrolyte Water Electrolysis

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 H2 and O2 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 bara. 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.