Flash-Combustion Synthesis of Self-Anchored Spinel Oxides via In Situ Ni Diffusion for Robust Water Oxidation

Constructing robust, binder-free electrodes with intimate substrate-catalyst contact is pivotal for advancing alkaline water electrolysis but remains impeded by complex synthesis procedures and weak interfacial adhesion. Herein, we present a rapid flash combustion synthesis strategy to fabricate a self-anchored Ni-Co-Fe spinel oxide electrode (Ni₁Co₁Fe₁O-NF) via in situ substrate diffusion. By exploiting the transient high-temperature thermal shock generated by igniting Co/Fe precursors on Ni foam, Ni atoms from the substrate are driven to diffuse outwards and react with the precursor layer. This process simultaneously establishes a compositionally graded, metallurgically bonded interface and a hierarchical porous network formed by gas expansion. The resulting Ni₁Co₁Fe₁O-NF electrode exhibits exceptional oxygen evolution reaction (OER) performance, requiring an overpotential of 254 mV to deliver a current density of 100 mA cm^-2 and maintaining industrial-level stability for over 1 week. Density functional theory (DFT) calculations reveal that the in situ incorporated Ni optimizes the electronic structure and triggers a switch from the conventional adsorbate evolution mechanism (AEM) to the energetically favorable lattice-oxygen-mediated (LOM) pathway. This work provides a scalable, energy-efficient paradigm for designing monolithic, high-performance electrodes for sustainable hydrogen production.