Performance and stability of a PEM water electrolyser based on different catalyst loadings and an Aquivion membrane

Membrane-electrode assemblies (MEAs) designed for water electrolysis, based on a short-side chain (SSC) perfluorosulphonic acid (PFSA) membrane, Aquivion® and varying in terms of cathode and anode noble metal loadings, were investigated in terms of performance and durability. Nanosized Ir0.7Ru0.3Ox solid solution anode and supported Pt/C cathode catalysts in combination with the Aquivion membrane, gave electrolysis performances exceeding 3.2 A·cm-2 at 1.8 V terminal cell voltage at 90 °C in the presence of a total catalyst loading of 1.6 mg?cm-2. A very small loss of efficiency corresponding to 30 mV voltage increase was recorded at 3 A?cm-2 using a total noble metal catalyst loading per MEA active area of less than 0.5 mg cm-2 vs. 1.6 - 2 mg cm-2. Steady-state durability tests, carried out for 1000 hrs at 1 A?cm-2, showed excellent stability for the MEA with total noble metal catalyst loading of 1.6 mg cm-2 (cell voltage increase ~ 5 ?V/h). An appropriate stability (cell voltage increase ~15 ?V/h) was also achieved for the low loading ~ 0.5 mg cm-2, MEA. This good combination of performance and stability for the developed MEAs was attributed to the enhanced proton conductivity and good mechanical stability of the novel membrane and the optimized structural properties of the Ir and Ru oxide solid solution. Ex-situ physico-chemical studies have indicated no relevant changes of the Ir/Ru ratio in the bulk after the durability test and a very slight increase of the Pt particle size.