MXene-Based Hierarchical Electron Coupling Engineering of F-Doped NiFe LDH/MOF-74 Electrocatalysts for Efficient Overall Water Splitting

Abstract

Enhancing the intrinsic activity and exposing the real active sites in transition metal-based electrocatalysts are still a formidable challenge. In this work, we introduce an efficient partial in situ transformation strategy (PTS) that converts the NiFe MOF-74 precursor into NiFe LDH@MOF composite structure, and subsequently the incoming F coordinates accelerate the structural reconstruction of F-doped NiFe LDH@MOF on MXene (F_d-PTS-NLM) during overall water splitting. The electrocatalytic mechanism exploration reveal that the rate of electron transfer in a material can be modulated by manipulating the electron diffusion process, thereby reducing the energy barrier associated with catalytic reactions. F-doping and PTS strategies effectively modify the d-band center and significantly improve the bifunctional activity of the catalyst. The results of in situ Raman characterization of F_d-PTS-NLM proved that metal hydroxyl oxides are the real active species in the OER reaction. In alignment with anticipated outcomes, the catalysts exhibited impressive electrochemical performance, with overpotentials of 150 mV and 171 mV for HER and OER at current densities of 10 mA cm^–2. Furthermore, a mere cell overpotential of 1.50 V was sufficient to generate a 10 mA cm^–2 current density in a two-electrode setup, F_d-PTS-NLM exhibited Faraday efficiencies (FEs) approaching 100%. The endurance of this material highlights its potential to minimize expenses in widespread industrial uses.