Electrochemical CO₂ reduction via strain-engineered AuPd alloy catalysts

Strain engineering offers a promising pathway to optimize catalytic performance by modulating electronic structures, yet the mechanistic role of surface strain in electrocatalytic CO₂ reduction (CO₂RR) remains insufficiently understood, hindering the rational design of high-performance catalysts for CO₂RR. In this work, we systematically elucidate the strain-activity relationship in AuPd alloy catalysts by developing a universal strain-tuning strategy through controlled lattice expansion of Pd cores in Pd@Au₄Pd₁ core-shell nanostructures. This approach enables the precise synthesis of Au-based catalysts with continuously tunable tensile strains (1.7 %–4.4 %). Flow cell measurements demonstrate that tensile-strained catalysts exhibit exceptional CO₂RR performance, achieving a CO faradaic efficiency of 94.1 % at −0.55 V vs. RHE, surpassing that of the unstrained counterparts (75.9 %) via suppressing competing hydrogen evolution. The CO partial current density increases linearly with strain magnitude, reaching 67.5 mA cm⁻² at −0.55 V for the optimal catalyst (4.4 % strain). Density functional theory calculations reveal that tensile strain lowers the energy barrier for the rate-limiting *COOH formation step and strengthens *CO adsorption attributed to an upward shift in the d-band center. These findings establish a quantitative correlation between lattice strain, electronic structure modulation, and catalytic behavior, providing a generalizable framework for engineering strain-optimized electrocatalysts for sustainable CO₂ conversion.