Multi-d-orbital hybridization tuning of IrFeCoNiMo high-entropy alloy for efficient alkaline oxygen evolution

IrFeCoNiMo HEA catalyst with multi-d-orbital hybridization is developed for alkaline OER. • IrFeCoNiMo shows 249 mV overpotential at 10 mA cm⁻² and 50.26 mV dec⁻¹ Tafel slope in 1 M KOH. • IrFeCoNiMo exhibits 32.2-fold higher TOF than IrO₂, with low charge transfer resistance and large surface area. • IrFeCoNiMo shows exceptional OER stability with only 1.2% overpotential decay after 5000 CV cycles and 40 h test. • Multi-d-orbital hybridization and HEA lattice distortion synergistically enhance OER performance. To address the bottlenecks of low catalytic efficiency and insufficient stability in the oxygen evolution reaction (OER) for water electrolysis hydrogen production, a multi-d-orbital synergistic modulation strategy is proposed, and the IrFeCoNiMo high-entropy alloy catalyst is fabricated via a solvothermal method. Composed of transition metals with distinct d-orbitals, the catalyst exhibits a single face-centered cubic (FCC) structure, uniform nanomorphology, and the coexistence of multiple valence states of metal elements. In alkaline electrolyte, it delivers a low overpotential of 249 mV at 10 mA cm −2 , a small Tafel slope of 50.26 mV dec −1 , and a turnover frequency (TOF) value 32.24 times higher than that of commercial IrO₂. Moreover, the catalyst demonstrates excellent stability after 5000 cyclic voltammetry (CV) cycles and a 40-h chronopotentiometry test. Mechanistic analysis confirms that the orbital hybridization induced by directional electron transfer among multiple d-electron orbitals, combined with the lattice distortion effect of high-entropy alloys, optimizes intermediate adsorption, increases active sites, and accelerates charge transfer. This study provides a new pathway for the design and development of high-performance alkaline OER catalysts, which is of great significance for promoting the large-scale application of water electrolysis hydrogen production technology. IrFeCoNiMo high-entropy alloy with multi-d-orbital hybridization is fabricated via solvothermal method. It exhibits ultrahigh alkaline OER activity (249 mV@10 mA cm −2 ) and exceptional stability, with TOF 32.24 times that of commercial IrO₂, attributed to optimized intermediate adsorption and accelerated charge transfer from orbital synergy and lattice distortion. Download: Download high-res image (87KB) Download: Download full-size image