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Abstract The design of high‐entropy single‐atom catalysts (HESAC) with 5.2 times higher entropy compared to single‐atom catalysts (SAC) is proposed, by using four different metals (FeCoNiRu‐HESAC) for oxygen reduction reaction (ORR). Fe active sites with intermetallic distances of 6.1 Å exhibit a low ORR overpotential of 0.44 V, which originates from weakening the adsorption of OH intermediates. Based on density functional theory (DFT) findings, the FeCoNiRu‐HESAC with a nitrogen‐doped sample were synthesized. The atomic structures are confirmed with X‐ray photoelectron spectroscopy (XPS), X‐ray absorption (XAS), and scanning transmission electron microscopy (STEM). The predicted high catalytic activity is experimentally verified, finding that FeCoNiRu‐HESAC has overpotentials of 0.41 and 0.37 V with Tafel slopes of 101 and 210 mVdec⁻¹at the current density of 1 mA cm⁻²and the kinetic current densities of 8.2 and 5.3 mA cm⁻², respectively, in acidic and alkaline electrolytes. These results are comparable with Pt/C. The FeCoNiRu‐HESAC is used for Zinc–air battery applications with an open circuit potential of 1.39 V and power density of 0.16 W cm⁻². Therefore, a strategy guided by DFT is provided for the rational design of HESAC which can be replaced with high‐cost Pt catalysts toward ORR and beyond. 

Abstract Functional unit and organization (FUO) paradigm starts with functional units and assembles these functional units into specific organizations to optimize material performance. An advantage of FUO paradigm is interpretation of physical essence of traditional structure–performance relationships. Experimental achievements based on FUO paradigm abound in recent years, demanding theoretical explanations for further quantitative material design. Following FUO paradigm, here a three‐step model (bond‐region‐structure) of nanotwin (NT) unit and orientation organization to optimize mechanical performance is established. First, anisotropic elasticities of representative bonds and assembled regional elastic constants are evaluated. Second, yield conditions of different regions, which are summarized as critical resolved shear stress (CRSS) criteria of NT structure, are quantified. Third, anisotropic yield strengths of NT structure from the regional elastic constants and CRSS criteria are derived. This FUO‐based model is implemented into InSb, GaAs, and ZnS, predicted elastic constants and yield strengths are validated with molecular dynamics (MD) simulations. The method is more efficient than MD with comparable accuracy, and is also flexible to combine with density function theory and experiment. This demonstration sets foundation of NT unit and orientation organization design for achieving optimum mechanical performance.