Strongly‐Interacted NiSe₂/NiFe₂O₄ Architectures Built Through Selective Atomic Migration as Catalysts for the Oxygen Evolution Reaction

Abstract The interactions between the catalyst and support are widely used in many important catalytic reactions but the construction of strong interaction with definite microenvironments to understand the structure‐activity relationship is still challenging. Here, strongly‐interacted composites are prepared via selective exsolution of active NiSe₂ from the host matrix of NiFe₂O₄ (S‐NiSe₂/NiFe₂O₄) taking advantage of the differences of migration energy, in which the NiSe₂ possessed both high dispersion and small size. The characteristics of spatially resolved scanning transmission X‐ray microscopy (STXM) coupled with analytical Mössbauer spectra for the surface and bulk electronic structures unveiled that this strongly interacted composite triggered more charge transfers from the NiSe₂ to the host of NiFe₂O₄ while stabilizing the inherent atomic coordination of NiFe₂O₄. The obtained S‐NiSe₂/NiFe₂O₄ exhibits overpotentials of 290 mV at 10 mA cm⁻² for oxygen evolution reaction (OER). This strategy is general and can be extended to other supported catalysts, providing a powerful tool for modulating the catalytic performance of strongly‐interacted composites.