Hierarchical Fe-based electrocatalyst for lattice oxygen mediated water oxidation with Industrial-Level activity

Rational design transition metal-based electrocatalysts for oxygen evolution reaction (OER) at large current densities is vital for industrial applications of alkaline water electrolysis. Here, we present a three-dimensional catalyst comprises of Fe₂O₃ nanoparticles that are highly dispersed on FeMoO₄ nanorods, supported on Ni foam, featuring a hierarchical heterostructure and array morphology. The resulting Fe₂O₃/FeMoO₄/NF electrodes exhibit remarkable OER catalytic activity, achieving overpotentials of 315 mV and 352 mV at current densities of 1000 mA cm^-2 and 2000 mA cm^-2, respectively, while maintaining outstanding long-term durability (>900 h) at a current density of 500 mA cm^-2. In-situ Fourier-transform infrared (FTIR) spectroscopy and theoretical studies demonstrate the direct OO radical coupling for lattice-oxygen-mediated mechanism (LOM)-dominated O₂ evolution, thereby breaking the scaling relationship limitation and accelerating reaction kinetics. Operando electrochemical impedance spectroscopy implies fast charge transport. The superior OER performance can be attributed to the abundant heterointerfaces between the active phases in hierarchical structure and the enhanced intrinsic activity through the LOM mechanism. This work paves an avenue for constructing advanced electrocatalysts with industrial-level activity and offering a promising approach for practical applications in alkaline water electrolysis.