Revealing the Interface-Driven Atomic Local Chemical Heterogeneity in Bimetallic Catalysts in Three Dimensions

Subsurface atomic configurations exert a profound influence on surface electronic structures, thereby playing a critical role in electrocatalysis. However, an in-depth understanding of intricate three-dimensional surface/subsurface structures in catalysts remains limited due to the weak interfacial signal and the inherent complexity in local structural and compositional nuances. Herein, by determining atomic structures in Pd@Pt model catalysts through atomic-resolution electron tomography, our investigation reveals the pivotal role of local chemical heterogeneity, driven by atomically interfacial diffusion at core-shell interfaces, in modulating electronic structures, thereby tuning the catalytic behavior in electrocatalytic ethanol oxidation reaction. Density functional theory calculations elucidate that atomically interfacial diffusion notably enhances OH adsorption energy at Pt sites while decreasing the CO adsorption energy at Pd sites on the surface by shifting the d-band center. These results broaden the existing paradigm of atomic interplay between surface and subsurface realms in catalysts at the fundamental level, offering valuable information for efficient catalyst design.