Carbonate electrolytes manipulate lattice oxygen dynamics of oxyhydroxides toward efficient and durable water oxidation

Activating the lattice oxygen of catalysts can accelerate the oxygen evolution reaction. However, a fundamental understanding of the lattice oxygen dynamics remains insufficient, which ultimately impairs catalyst development. Herein, we show that a CO32--containing electrolyte can substantially alter the reactivity and redox stability of lattice oxygens. In particular, for CoOOH and NiCoOOH, which feature high lattice oxygen reactivity, higher degrees of CO32- intercalation deactivate lattice oxygen, shifting the reaction pathway from the lattice oxygen mechanism to the adsorbate evolution mechanism. Operando spectroscopic and spectrometric analyses coupled with 18O isotopic labeling corroborate the decreased metal‒oxygen bond covalency and hindered lattice oxygen release caused by the intercalation of CO32-. Importantly, the catalysts with a fine-tuned degree of CO32- intercalation maintain high activity and stability owing to the dynamic equilibrium between lattice oxygen release and refilling, demonstrating negligible degradation in an alkaline water electrolyzer after 5000 h of operation at 0.5 A cm-2. This work reveals the intricacy of lattice oxygen dynamics, offering opportunities for designing high-performance electrocatalysts for real-life applications. The dynamics of lattice oxygen in oxyhydroxide catalysts is crucial for water oxidation but are not fully understood. Here, the authors report that carbonate ions in the electrolyte can substantially alter the dynamics, leading to robust long-term stability with sustained lattice oxygen reactivity.