Hybrid anode design of polymer electrolyte membrane water electrolysis cells for ultra-high current density operation with low platinum group metal loading

Reducing platinum group metal (PGM) loading and high current density operation are both essential for minimizing the capital expenditure (CAPEX) of polymer electrolyte membrane (PEM) electrolyzers. Catalyst-integrated porous transport electrodes (PTEs) in which iridium acts as both a catalyst and a conductive coating on porous transport layer (PTL) surfaces, enable the preparation of Pt-coating-free PTLs, but can also result in relatively high activation and ohmic overvoltages. Here, a novel hybrid anode design combining an intermediate catalyst layer and a catalyst-integrated PTE is developed. This hybrid anode demonstrates that Ir on PTL can contribute to the oxygen evolution reaction (OER) and exhibits comparable electrolysis performance to a conventional anode consisting of Pt-coated PTL with the same Ir loadings despite Pt-coating-free on the PTL of the hybrid anode. This novel anode eliminates the need for a Pt coating whilst also enabling ultra-high current density operations up to 20 A cm⁻² with a total PGM loading of only around 0.6 mg cm⁻² on the anode side. This paper proposes a next-generation anode structure with new functions of PTLs for ultra-high current density operation with low PGM loading to significantly reduce green hydrogen costs.