Synergistic regulation of morphology and electronic coupling of dual-ligand NiFe MOF for efficient electrocatalysis in multi-electrolyte water splitting

Abstract

Our study achieves efficient electrocatalysis for the electrooxidation reaction in multi-electrolyte systems by synergistically modulating structure and electronic coupling through rational design. We establish novel principles for controlling the morphology and performance of metal-organic frameworks (MOFs): Formation of nano-flower structure requires co-existence of Ni site and Fc ligand, doping of Fe sites promotes three-dimensional (3D) crystal morphology development, which marks a pioneering advance in the field. Among them, the bimetallic dual-ligand MOF: NiFe-BDC/Fc (NFBF)(6:2) exhibits outstanding electrocatalytic performance (210 mV at 10 mA·cm⁻²). <i>Operando</i> Raman spectroscopy and X-ray absorption fine structure (XAFS) reveal the electronic restructuring feature of NFBF(6:2) during the catalytic oxygen evolution reaction (OER) process. Combined with density functional theory (DFT) calculations, which identify Ni as the catalytic active site, these investigations uncover significant electronic migration and redistribution, substantially reducing the reaction energy barrier and accelerating the catalytic process. Comprehensive exploration demonstrates that NFBF(6:2) not only performs well under various multi-electrolyte conditions but also maintains a nearly consistent catalytic mechanism. Furthermore, when applied to overall water splitting, (+) NFBF(6:2) || NFBF(6:2) (−) achieves significant catalytic effects in both alkaline freshwater (1.40 V at 10 mA·cm⁻²) and seawater (1.44 V at 10 mA·cm⁻²) electrolyzers. This work highlights the crucial role of electronic coupling in optimizing electrocatalytic performance and offers new insights for addressing mitigating environmental pollution, embodying substantial practical and research potential.

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