Creating Atomic-Level Alkaline Microenvironment by Constructing Fe-O and Cr-O Ligands on CoO to Enhance Neutral Water...

Developing active and stable oxygen evolution reaction(OER) electrocatalysts for water-splitting hydrogen production under neutral conditions is crucial. Introducing Lewis acid (LA) on catalysts surface can build local alkaline microenvironment to enhance OER, but it may reduce active site exposure. In this work, atomic-level LA sites (Fe-O and Cr-O ligands) are constructed and decorated CoO (designated as FeCr-CoO), in which the Cr-O ligands can accelerate the transfer of ^*OH to OH⁻ and form a local alkaline environment, Fe-O ligands can prevent Cr-O ligands from being oxidized and thus improving the durability of FeCr-CoO during the OER process. Moreover, the synergistic effect between Fe-O and Cr-O ligands can not only boosts the Lewis acidity, but also effectively promotes the water dissociation process (H₂O^*→^*OH+^*H) and ensures the prompt supply of ^*OH in the elementary reaction from ^*O to ^*OOH. Therefore, the FeCr-CoO achieved a low OER overpotential of 214 mV at 10 mA cm^-2 and displayed negligible degradation in 1000 h in neutral electrolyte. Additionally, the overall water-splitting electrolyzer can reach 10 mA at 1.50 V, and is kept stable for over 500 h with a degradation of only 5.3%. This study provides a new way for designing efficient OER catalysts under neutral conditions by constructing local alkaline microenvironments.