Intrinsic activation regulation of ZIF-67 derived Co3O4/NF with multi-level multidimensional nanostructure for oxygen evolution reaction

Abstract

The slow oxygen evolution reaction (OER) caused by intrinsic active site deficiency for cobalt-based catalyst is a major challenge but is key to unlocking its water electrolysis potential. Here, ZIF-67 dirved Co₃O₄/NF with multi-level multidimensional nanostructure is regulated by NaBH₄ reduction and Fe etching (Fe-V_O-Co₃O₄-ZIF/NF). Fe-V_O-Co₃O₄-ZIF/NF exhibits an overpotential of 299 mV at the current density of 100 mA cm⁻² and a Tafel slope of 35.4 mV dec⁻¹ in 1.0 M KOH, as well a good stability at high current desity. The online electrochemical and Tauc plot reveal that oxygen vacancies and Fe regulation could effectively enhance the conductivity and improve the intrinsic activity of cobalt-based catalyst during water electrolysis. Physicochemical characterization and electrochemical test reveal that the electronic structure of Co₃O₄-ZIF/NF is synergistically regulated by increased of oxygen vacancy and Fe active sites, which results in an intrinsic surficial activity enhancement. While the theoretical calculation based on the density functional theory (DFT) presents the adsorption/desorption enhancement of reaction intermediates (OH∗, O∗, and OOH∗) mechanism of Fe-V_O-Co₃O₄-ZIF/NF in the OER step-determined elemental reaction. Our approach underscores the significance of sturcture defect engineering and element-interaction atrategies in advancing the intrinsic activity regulation of the ORE catalyst during water electrolysis.