Lattice strain engineering of iridium-based catalysts for acidic oxygen evolution reaction.

Iridium (Ir)-based catalysts are indispensable for acidic oxygen evolution reaction (OER) in proton exchange membrane water electrolysis (PEMWE). Among the structural parameters governing catalytic behavior, lattice strain has emerged as a pivotal factor that bridges atomic arrangement, electronic structure, and reaction pathways. This review provides a focused overview of strain engineering in Ir-based catalysts for acidic OER to advance both catalyst design and mechanistic understanding. We first outline the fundamentals of lattice strain and acidic OER, followed by a summary of the principal strategies used to generate strain in Ir-based systems. Emphasis is placed on interface-induced, composition-modulated, and defect-induced strain as effective approaches for tuning catalytic activity and stability. We further discuss the mechanistic roles of strain in regulating adsorption behavior, electronic states, and reaction pathways at the atomic level. By integrating recent experimental and theoretical advances, this review establishes a coherent framework for understanding strain-activity-stability relationships in Ir-based catalysts. The insights summarized herein are expected to guide the rational development of efficient, durable, and economically viable Ir-based catalysts for practical PEMWE applications.