Platinum functional layer for hydrogen crossover mitigation in proton exchange membrane water electrolysers

• A platinum functional layer introduced at the anode/PEM interface to mitigate hydrogen crossover. • Minimal platinum loading of 2 µg/cm 2 achieves significant hydrogen crossover reduction by 73 % • Mechanism insights reveal the contribution of the platinum functional interlayer by HOR. • Outstanding durability under dynamic conditions support the application in renewable energy-driven PEMWEs. Hydrogen crossover presents a significant challenge for proton exchange membrane water electrolysers (PEMWEs), particularly during differential pressure operation. This study demonstrates a platinum functional layer at the anode and membrane interface for reducing hydrogen crossover under differential pressure operation in PEMWEs. The functional layer, with 1 nm equivalent thickness, is deposited on PEM surface at the anode side using sputter coating. The results show 73 % and 23 % reduction in hydrogen crossover at 0.25 A/cm 2 in the single cell test during 0-bar and 10-bar differential pressure operation, respectively, highlighting the layer’s effectiveness across different pressures. To evaluate durability, an accelerated stress test is conducted to simulate the dynamic operational condition. The functional layer retains more than 94 % of its hydrogen crossover mitigation capability at 0.25 A/cm 2 and 99 % at 2.50 A/cm 2 at 10 bar pressure difference, indicating excellent durability and a highly positive role of this functional layer for high pressure operation.