Application and performance Enhancement of acetic acid-Regulated ligand defect engineering in NiMOF electrocatalysts

Abstract

Introducing organic ligands into metal-organic frameworks (MOFs) is an effective method for preparing defective MOFs. This approach enables the fabrication of cost-effective, efficient, highly conductive, and richly active-site electrocatalysts. Herein, the defective NiMOF is synthesized via a straightforward one-pot solvothermal method by partially substituting phthalic acid (PTA) ligands with acetic acid (HOAc), which effectively regulates the micro-morphology and electronic structure of the NiMOF nanoflowers, thus creating abundant electrochemical active sites, significantly improving electronic conductivity and promoting rapid charge transfer. The resulting DE-NiMOF-0.5 nanoflowers, prepared with HOAc substitution, demonstrate excellent electrochemical performance at a current density of 10 mA cm⁻², the hydrogen evolution reaction (HER) overpotential is 188 mV (Tafel slope of 175 mV dec⁻¹), while the oxygen evolution reaction (OER) overpotential is 205 mV (Tafel slope of 37 mV dec⁻¹). The introduction of acetic acid ligands in DE-NiMOF-0.5 not only constructs the ligand defects within the catalyst, but also increases the abundant active sites, enhancing the hydrophilicity of the catalyst and facilitating electronic transfer between the catalyst surface and the electrolyte. This study explores a strategy for preparing defective MOF catalysts through introducing modulators, providing an economically viable material pathway for electrocatalysis and opening new possibilities for designing and synthesizing efficient electrocatalysts in future research endeavors.