Rational Design of Single-Atom Alloy Catalysts from PtAu₂₄ Nanoclusters toward Enhanced Electrochemical Activity

Single-atom alloys (SAAs) have emerged as a unique class of catalysts that integrate the advantages of conventional alloy systems with those of single-atom catalysts. The maximized utilization of isolated atomic active sites in SAAs enables efficient catalytic processes across a wide range of electrocatalytic reactions. Herein, a series of heteroatom-doped Au₂₅ nanoclusters (NCs) were synthesized as model SAA catalysts, where the catalytic activity of Au₂₅ NCs could be precisely tuned by incorporating a single Pt atom into the nanocluster kernel. Density functional theory (DFT) calculations reveal that such atomic-level heteroatom engineering modulates the electronic structure and adsorption energetics of key intermediates. PtAu₂₄ approaches the Sabatier optimum for the oxygen reduction reaction (ORR), whereas Pd substitution induces overbinding of *O species, leading to diminished catalytic activity. This work provides fundamental insights into the design of single-atom-doped bimetallic catalysts and offers a viable strategy for improving the electrocatalytic performance.