From Instability to Design Principle: Rethinking Ir‐Free Catalysts for Acidic OER

The instability of non‐noble catalysts in the acidic oxygen evolution reaction (OER) is not merely a materials limitation, but a fundamental consequence of thermodynamic constraints under highly oxidative conditions. Here, we present a unified perspective that reinterprets this instability as a thermodynamically driven and kinetically modulated process, rather than an intrinsic material deficiency. This review covers the fundamental origins of catalyst degradation in acidic OER, including the lack of thermodynamically stable phases and the activity‐stability trade‐off. We further discuss emerging strategies such as compositional engineering, entropy stabilization, and functional decoupling, which can expand stability windows and alleviate bulk instability while maintaining surface reactivity. Finally, we highlight insights from operando studies that uncover dynamic reconstruction, dissolution, and redeposition processes under operating conditions. By integrating thermodynamic design, kinetic control, and multiscale structural engineering, this perspective outlines emerging strategies to transform instability into a controllable feature, offering new directions for designing durable, earth‐abundant OER catalysts.