Method for preparing a polymer membrane for a polymer electrolyte water electrolyser

A method of preparing an ionomer of an ion exchange membrane with a recombination catalyst to prevent gas crossover of species to anodic and cathodic cell compartments of an electrochemical cell, the method comprising the steps of:

• a) providing the ionomer of the ion exchange membrane as a proton or an anion exchange polymer;
• b) selecting the recombination catalyst from the precious metals group;
• c) providing the recombination catalyst selected in step b) in an ionic form in a liquid metal salt solution;
• d) immersing the ion exchange membrane into the liquid metal salt solution to thereby exchange at least a part of the ion exchange sites with the ionic form of the recombination catalyst;
• e) assembling the immersed ion exchange membrane in the electrochemical cell;
• and
• f) subsequently at least partially reducing the ionic form of the recombination catalyst into a metallic form by providing hydrogen gas at an elevated pressure on one side of the ion exchange membrane and forcing the hydrogen to permeate from the one side through the ionomer of the ion exchange membrane inside the electrochemical cell.