Stainless Steel Felt as a Combined OER Electrocatalyst/Porous Transport Layer for Investigating Anion-Exchange Membranes in Water Electrolysis

Anion-exchange membrane water electrolysis (AEMWE) is a promising technology for low-cost, high-efficiency, green hydrogen production. The stability of the AEM is a critical issue but difficult to delineate in situ from degradation of the catalyst layer (CL). Moreover, the porous transport layer (PTL) can contribute electrocatalytically. Herein, we demonstrate that stainless steel (SS) felt, in the absence of an anode CL, is highly active toward the oxygen evolution reaction (OER) (1 A cm–2 at 1.74 Vcell) and serves as a combined OER electrocatalyst and PTL, thus simplifying the study of AEMs in water electrolyzers. We further show that Ni felt exhibits much lower OER activity than SS felt, which suggests that in situ studies of OER electrocatalysts and CL compositions should be performed with Ni felt, not SS felt, to reduce OER contributions from the PTL. Lastly, we found that the substrate for depositing the cathode CL, AEM, or PTL strongly influences the rate of H2 crossover.