Activating and Stabilizing Lattice Oxygen in Cobalt Oxyhydroxide for Efficient Water Oxidation

Although activating lattice oxygen to participate in the O–O coupling process and suppress the formation of *OOH species has been proven to be an efficient strategy for boosting the kinetics of the oxygen evolution reaction (OER), the generation of lattice oxygen vacancies during the catalytic cycle usually leads to structural collapse and degraded stability. Herein, through cationic vacancy engineering, we propose that the lattice oxygen in VAl-CoOOH can be simultaneously activated and stabilized, therefore achieving efficient and durable alkaline OER. Structural investigations and theoretical calculations reveal that introducing cationic vacancies in CoOOH causes increased Co–O hybridization and drives the kinetically favorable lattice oxygen oxidation (LOM) mechanism. More critically, spectroscopy experiments, including operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy and in situ X-ray absorption spectroscopy, demonstrate the dynamic evolution of the interfacial water structure in the electric double layer (EDL), with VAl-CoOOH displaying a much enhanced population of isolated water molecules (K·H2O), which is essential for the rapid replenishment of lattice oxygen, thereby leading to a superior and stable lattice-oxygen-mediated OER process. This work highlights the significant potential of interfacial water structure regulation in the EDL toward efficient and durable lattice-oxygen-mediated water oxidation.