Designing durable and efficient Co-based catalysts for acidic oxygen evolution reaction in proton exchange membrane water electrolyzers

Proton exchange membrane water electrolyzers (PEMWEs) are pivotal for efficient hydrogen production due to their high energy efficiency and ability to operate at high current densities, making them ideally suited for integration with renewable energy sources. Cobalt (Co)-based nanomaterials, characterized by diverse oxidation states, tunable electronic spin states, and hybrid orbitals, have emerged as promising non-noble metal alternatives to platinum group catalysts for accelerating the anodic oxygen evolution reaction (OER). Based on their inherent properties, this review provides a comprehensive overview of the latest developments in Co-based nanomaterials for acidic OER. The review begins by introducing the operational principles of PEMWEs, the underlying catalytic mechanisms, and the critical design considerations for OER catalysts. It then explores strategies to enhance the activity and stability of Co-based catalysts for acidic OER in PEMWEs, including the incorporation of corrosion-resistant metals or dispersion on acid-resistant supports to increase active surface area and stability; utilization of geometric structural engineering to improve structural integrity and active site efficiency; the optimization of reaction mechanisms to fine-tune catalytic pathways for enhanced stability and performance. The performance degradation mechanisms and metal leaching analysis for Co-based catalysts in PEMWE are also clarified. Finally, this review not only outlines the key challenges associated with Co-based catalysts for acidic OER but also proposes potential strategies to overcome these limitations, offering a roadmap for future advancements and practical implementation of PEMWE technology.