The Tradeoff behind Optimal 3-Fold (C,N)-Coordinated Single-Atom Catalysts

Abstract Single-atom catalysts have emerged as a powerful class of catalytic materials, maximizing atom efficiency through isolated metal centers. However, their design inherently relies on a delicate balance between stability and catalytic performance. In this work, we investigate this tradeoff by systematically analyzing trends in formation, adsorption, and reaction energy at the catalyst surface for the partial hydrogenation of butadiene. Our results reveal clear opposite relationships between these features: increasing the number of nitrogen neighbors (Ndop) enhances stability, whereas lower Ndop favors catalytic activity. Adsorption energies are shown to scale with the product Zm × Ndop, where Zm is the atomic number of the isolated metal. They also exhibit a weaker linear dependence on the catalyst d-states and HOMO-LUMO gap of the adsorbate. By extending this physically grounded model across the periodic table, we provide a framework for the rational optimization of single-atom catalysts through dedicated scoring functions.