Activating the Basal Planes and Oxidized Oxygens in Layer-Structured Na_0.6 CoO₂ for Boosted OER Activity

With the CoO₂ slabs consisting of Co₄ O₄ cubane structure, layered Na_x CoO₂ are considered promising candidates for oxygen evolution reaction (OER) in alkaline media given their earth-abundant and structural advantages. However, due to the strong adsorption of intermediates on the large basal planes, Na_x CoO₂ cannot meet the activity demands. Here, a novel one-pot synthesis strategy is proposed to realize the high solubility of iron in Na_x CoO₂ in an air atmosphere. The optimist Na_0.6 Co_0.9 Fe_0.1 O₂ exhibits enhanced OER activity compared to their pristine and other reported Fe-doped Na_x CoO₂ counterparts. Such an enhancement is mainly ascribed to the abundant active sites on the activated basal planes and the participation of oxidized oxygen as active sites independently, which breaks the scaling relationship limit in the OER process. This work is expected to contribute to the understanding of the modification mechanism of Fe-doped cobalt-based oxides and the exploitation of layer-structured oxides for energy application.