Atomically Dispersed Amorphous FeCo-SiWA Catalysts Enable Efficient OER via Lattice Oxygen-Mediated Mechanism

Developing stable amorphous multimetal oxides for the anodic oxygen evolution reaction (OER) remains challenging due to structural instability and inhomogeneity. Herein, a polyoxometalate (POM)-assisted strategy is presented to fabricate amorphous multimetal oxides (Fe_yCo_{1- y}O_x-SiWA) featuring atomically dispersed metal sites and exceptional alkaline stability. Sub-nanometer [SiW₁₂O₄₀]^4- (SiWA) clusters interact strongly with Fe³⁺, locking the metal-oxygen network into a disordered yet stable architecture, suppressing phase segregation and ultimately enabling OER activity. The Fe_0.3Co_0.7O_x-SiWA achieves ultralow OER overpotentials of 277/330 mV at 10/100 mA cm^-2, a Tafel slope of 44.6 mV dec^-1, and an industrial-grade potential of 1.8 V (vs RHE) at 1000 mA cm^-2, surpassing commercial RuO₂ and most non-noble catalysts reported to date. Comprehensive mechanistic investigations employing ¹⁸O^- labeled differential electrochemical mass spectra (DEMS), in situ infrared, in situ Raman spectroscopy and density functional theory (DFT) calculations revealed a lattice oxygen-mediated (LOM) pathway that allows for direct O─O coupling, bypassing the rate-limiting OOH* formation step in conventional adsorbate evolution mechanism (AEM) pathways. Atomic disorder in the amorphous multi-metal oxides promotes lattice oxygen participation, as validated by both theoretical and experimental evidence. This work provides a paradigm for engineering cluster-stabilized amorphous oxides while advancing mechanistic understanding of high-current-density electrocatalysis through synergistic structure-property insights.