Development of Efficient Catalyst Layers for Proton Exchange Membrane Water Electrolysis: The Role of Catalyst Supports

Abstract Proton exchange membrane water electrolysis (PEMWE) is a promising technology for green hydrogen production, but requires a high iridium (Ir) loading of ≈2.0 mg cm −2 in the anode catalyst layer (CL), which increases capital costs and hinders the scalability of system deployment. Conventionally, non‐supported IrO 2 has been used in the form of film CL, but these structures struggle to maintain sufficient performance at lower Ir loadings, making it difficult to reduce Ir content below 0.1 mg cm −2 . Lower Ir loading leads to higher electrical resistance and localized hot spots, ultimately causing performance losses. Introducing catalyst supports can address these issues by improving catalyst utilization and enabling the development of efficient CL. While previous studies have primarily focused on advanced electrocatalysts, this review highlights the role of catalyst supports in fabricating efficient CL. It provides a comprehensive overview of recent advancements in catalyst support materials for PEMWE, with a focus on oxide‐based supports, non‐oxide ceramics, highly crystalline carbon, and hybrid composites. By examining fundamental challenges and emerging strategies in support design, this review offers critical insights into advancing high‐efficiency, cost‐effective, and durable PEMWE systems for large‐scale green hydrogen production.