Fabrication of FeCoNi LDH medium entropy hydroxide nanosheet for catalyzing oxygen evolution reaction

Medium entropy material-based catalysts have garnered increasing attention in water electrolysis due to their high electrocatalytic activity and excellent stability, which are attributed to lattice distortion and hysteretic diffusion effects. In this study, we successfully fabricated 3D nanoflower-like array of FeCoNi layered double medium entropy hydroxide (ME-LDH) nanosheets for the oxygen evolution reaction (OER) through a one-step hydrothermal synthesis method. Subsequently, the FeCoNi LDH was activated via NaClO oxidation treatment, thereby modulating the valence states of the metallic elements. The performance of the activated FeCoNi LDH (A-FeCoNi LDH) was further optimized by precisely adjusting the hydrothermal temperature and metal ion concentration. Benefiting from its unique nanostructure, lattice distortion, and multiple active sites, the A-FeCoNi LDH coated electrode demonstrates superior OER electrocatalytic performance, achieving a low overpotential of 228 mV and a low Tafel slope of 58.37 mV dec⁻¹ to deliver a current density of 10 mA cm⁻², along with remarkable long-term stability exceeding 80 h. This work provides an innovative strategy for developing efficient medium entropy electrocatalysts, showcasing significant potential for practical industrial applications.