ABSTRACT Hydrocarbon (HC) membranes have the potential to significantly enhance the efficiency of water electrolyzers. However, their low mechanical integrity under electrolysis conditions, due to severe swelling, poses a challenge for industrial‐scale applications. Here, we present a 12 µm‐thick sulfonated poly(phenylene sulfone) (sPPS) membrane reinforced with a porous polyethylene (PE) substrate. The PE substrate reduces in‐plane swelling by a factor of 7 (10% vs 69%) and improves mechanical stability (440 MPa vs 50 MPa) in water at 60°C. Under electrolysis conditions, a 24 µm thick sandwich of two reinforced membranes shows stable operation over more than 2000 h in a constant current hold at 1 A cm −2 conducted at 60°C (first 1000 h) and 80°C (remaining 1000 h) with only 6 µV h −1 of voltage deviation within the last 500 h. With a potential of 1.67 V and a hydrogen in oxygen content of 1 vol% at 3 A cm −2 , the PFAS‐free membrane clearly outperforms a state‐of‐the‐art reference (Nafion‐N211: 1.73 V and 1.5 vol% at 3 A cm −2 ).
Schare et al. (Tue,) studied this question.