Nest‐Scheme RuIrLa Nanocrystals by NP‐to‐NP Oriented Assembly: Coherent Strain Fields‐Driven Band Structure Splitting for Efficient Acidic Water Oxidation

Abstract Atomic substructure engineering provides new opportunities for the designing newly and efficient catalysts with diverse atom ensembles, trimmed electron bands, and way‐out coordination environments, creating unique contributing to concertedly catalyze water oxidation, which is of great significance for proton exchange membrane water electrolysis (PEMWE). Herein, nest‐scheme RuIrLa nanocrystals with dense coherent interfaces as built‐in substructures are firstly fabricated by using commercial ZnO particles as acid‐removable templates, through a La‐stabilized coherent epitaxial growth of nanoparticles (NPs). The obtained nests exhibit a low overpotential of 198 mV at 10 mA cm ⁻² , and the RuIrLa||Pt/C module equipped in PEMWE operates stably at a cell voltage potential of 1.69 V at 100 mA cm ⁻² in 0.5 M H ₂ SO ₄ for 55 h, which is far beyond the current IrO ₂ ||Pt/C. Within the nests, the position at the interface shows high tensile/compressive strain, significantly reducing the OER activation energy. More importantly, the La termination‐stabilized coherent interfaces within the nests creates a unique self‐healing process for the outstanding long‐term stability. This work provides a promising substructure engineering to develop efficient catalysts with abundant substructures, such as coherent interfaces, dislocations, or grain boundaries, thereby realizing concerted improvement of activity and durability toward water oxidation.