Understanding of Strain Effects in the Electrochemical Reduction of CO2: Using Pd Nanostructures as an Ideal Platform

Tuning the surface strain of heterogeneous catalysts represents a powerful strategy to engineer their catalytic properties by altering the electronic structures. However, a clear and systematic understanding of strain effect in electrochemical reduction of carbon dioxide is still lacking, which restricts the use of surface strain as a tool to optimize the performance of electrocatalysts. Herein, we demonstrate the strain effect in electrochemical reduction of CO2 by using Pd octahedra and icosahedra with similar sizes as a well‐defined platform. The Pd icosahedra/C catalyst shows a maximum Faradaic efficiency for CO production of 91.1 % at −0.8 V versus reversible hydrogen electrode (vs. RHE), 1.7‐fold higher than the maximum Faradaic efficiency of Pd octahedra/C catalyst at −0.7 V (vs. RHE). The combination of molecular dynamic simulations and density functional theory calculations reveals that the tensile strain on the surface of icosahedra boosts the catalytic activity by shifting up the d‐band center and thus strengthening the adsorption of key intermediate COOH*. This strain effect was further verified directly by the surface valence‐band photoemission spectra and electrochemical analysis. No strain, no gain: Pd octahedra and icosahedra with similar sizes are used as a well‐defined platform to study the effect of surface strain in electrochemical reduction of CO2. The results show that tensile strain improves catalytic activity by shifting up the d‐band center and thus strengthening the adsorption of key intermediate COOH*.