Disentangling Electronic and Strain Effects in Core–Shell Pd@Pt Catalysts

Enhancing intrinsic catalytic activity through material engineering remains a key objective in electrocatalysis research. To achieve this, constructing/assembling nanoscale core-shell structures has proven a particularly effective strategy, as it can simultaneously enhance catalytic activity and optimize atom utilization. The altered/modulated electrocatalytic properties of the shell can arise from lattice strain, induced by core-shell lattice mismatch, together with ligand effects, reflecting electronic interactions between heteroatoms. However, synthetically, it is difficult to isolate/separate the strain effect from electronic interactions, making the specific contribution/attribution to altered catalytic activity ambiguous. Here, we report a Pd@Pt core-shell nanocube (NC) system in which the Pd core, with expanded lattice parameters, minimizes its strain effect on the Pt shell. The Pt shell exhibits a more than 10-fold increase in catalytic activity compared to pure Pt NCs for both the hydrogen oxidation (HOR) and oxygen reduction (ORR) reactions under alkaline conditions. X-ray photoelectron spectroscopy analysis revealed a downshift of the Pt d-band center, and density functional theory calculations indicate that this change arises predominantly from electronic effects rather than strain effects, weakening the binding strength of reaction intermediates and thereby enhancing electrocatalytic activity. This work highlights the significance of electronic effects in tuning electrocatalytic activity.