Tuning the d‐Band Center via Strain and Ligand Effects in Core–Shell Pentatwinned Au@Pd Nanoparticles for Enhanced Ethanol Oxidation Reaction

Abstract The successful commercialization of direct ethanol fuel cells (DEFCs) hinges on the development of highly efficient electrocatalysts capable of overcoming key performance limitations. In this study, the core–shell Au@Pd pentatwinned decahedral nanoparticles has been synthesized with controlled Pd shell thicknesses, varying in the average number of Pd monolayers over the Au core. This core‐shell configuration promotes the epitaxial growth of Pd atoms with varying degrees of tensile strain. Density functional theory (DFT) calculations reveal that increasing tensile strain shifts the d‐band center closer to the Fermi level. Notably, when the Pd shell is three monolayers, the upward shift of the d‐band center is maximum, and this further amplified by the ligand effect from the underlying Au core. The synergistic influence of five twin boundaries, tensile strain, and ligand interactions collectively tunes the d‐band center, resulting in the Au@Pd‐3 catalyst achieving an exceptional mass activity of 25.67 A mg Pd −1 and a specific activity of 21.30 mA cm −2 , representing enhancements of 38.31‐fold and 11.39‐fold, respectively, over commercial Pd/C. This study highlights how the combined effects of strain and ligand interactions can be strategically harnessed to design high‐performance electrocatalysts by tuning the position of d‐band center.