Open-circuit dissolution of platinum from the cathode in polymer electrolyte membrane water electrolysers

Platinum is the state-of-the-art catalyst for hydrogen evolution in polymer electrolyte membrane (PEM) water electrolysers; however, its stability has only been characterized to a limited extent situ. This study measures platinum dissolving from cathode during intermittent operation of 3-electrode PEM electrolyser cell, using differential pulse voltammetry technique that provided detection limits less than 2 ng L−1. Water samples were periodically taken on-off current cycling, and periods open-circuit voltage (OCV) dissolution was detected when potential rose above 0.85 V NHE due diffusion oxygen anode. reached maximum rate at highest 1.02 NHE, gradually decayed over 90 h period. The average total amount dissolved per OCV period estimated be 152 cm−2 or 0.005% initial electrode mass. mechanism predicted same as occurring fuel cell cathodes, although being kinetically hindered electrolysers by slow anode cathode.