Different\nFeS Concentrations for Encapsulating ZIF-67\nNanomaterials toward the Enhanced Oxidation Evolution Reaction

Due to the slow kinetic nature of the oxygen evolution\nreaction\n(OER), the development of electrocatalysts with high efficiency, stability,\nand economy for oxygen production using metal–organic framework\n(MOF) materials is still a challenging research topic. In this work,\nwe chose the different concentrations of FeS adsorption to encapsulate\nmetal cobalt-based ZIF-67 MOF for preparing a series of electrocatalysts\n(ZIF<sub>1</sub>FeS<sub><i>x</i></sub>, <i>x</i> = 0.2, 0.5, 0.75, and 1), which were mainly explored for the electrocatalytic\nOER. Among them, ZIF<sub>1</sub>FeS<sub>0.5</sub> has excellent electrocatalytic\nactivity for OER, which can be driven by low overpotentials of 276\nand 349 mV at 10 and 50 mA cm<sup>–2</sup> current densities,\nand more than 92% of the initial overpotential can be maintained after\n100 h of continuous OER at 10 mA cm<sup>–2</sup> current density.\nThis is mainly due to the electronic interactions between the cobalt-based\nMOF and the FeS, which shift the electronic state of the active metal\ncenter to a higher valence state for increasing the number of active\nsites and enhancing the efficiency of electron transfer to facilitate\nthe OER course. This work may contribute to the design of effective\ncatalysts for the OER during the electrolysis of alkaline solutions.