Construction of self-supporting bimetallic organic frameworks electrocatalysts and investigation of their electrocatalytic oxygen evolution reaction performance

Abstract

The development of non-precious metal electrocatalysts with high activity and stability is pivotal to advancing water electrolysis technology. Although metal-organic frameworks (MOFs) offer advantages such as tunable structures and well-defined sites, conventional powdered electro-catalysts commonly suffer from issues including deactivation and de-tachment of active sites, as well as poor conductivity. To address this, this work employs an in-situ synthesis strategy on a substrate. Using nick-el-iron foam as both substrate and metal source, a one-step solvothermal method successfully grows arrays of nickel-iron bimetallic MOF nanosheets directly onto the framework surface, constructing a binder-free, self-supporting electrode (NiFe-MIL, MIL stands for Materials Institute Lavoisier). In situ growth ensures robust chemical bonding and efficient electron transfer between the MOF active layer and conductive substrate, fundamentally eliminating active site shielding and detachment issues caused by insulating binders. The bimetallic synergistic effect optimises the material's electronic structure at the atomic level, effectively modulating the adsorption energy of oxygen-containing intermediates and thereby sig-nificantly enhancing intrinsic activity. Benefiting from this unique struc-tural design, the fabricated NiFe-MIL electrocatalyst exhibits an overpo-tential of merely 265 mV at 10 mA cm⁻² in 1 M KOH electrolyte, with a Tafel slope as low as 41.4 mV dec⁻¹. It also demonstrates impressive elec-trocatalytic durability. This work not only validates the feasibility of uti-lising substrates as in situ metal sources for MOF construction but also provides novel insights for designing highly efficient and stable bimetallic electrodes.