Oxyanions as dynamic regulators of the oxygen evolution reaction

transformations as regulators of these interfacial states. We argue that oxyanions are neither passive spectators nor single chemical modifiers; instead, they actively couple electronic structure, charge transport, and reaction pathways across multiple length and time scales. We formalize the OER interface as a nonequilibrium, dynamic interfacial ensemble: a continuously exchanging population of solid and molecular species, including oxyanions, whose coordination environment, coverage, and microstructure evolve under bias. Within this framework, oxyanion coordination, exchange, and residence time serve as time-dependent control parameters that generate emergent interfacial properties, macroscopic activity, selectivity, and stability, through collective, temporally evolving interactions rather than any single static active-site descriptor. Oxyanions reshape reaction free-energy landscapes, tune adsorption energetics, and in selected cases alleviate conventional scaling relationships, enabling mechanistic regimes beyond adsorbate-only descriptions. We also outline key limitations of current predictive frameworks and propose interface-centric design strategies that remain effective under operational conditions.