(661j) Planar Defect-Driven Electrocatalysis of CO2-to-C2H4 Conversion

The selectivity towards a specific C₂₊ product, such as ethylene (C₂H₄), is sensitive to the surface structure of copper (Cu) catalysts in the CO₂ electro-reduction reaction (CO₂RR). The fundamental understanding of such sensitivity can guide the development of advanced electrocatalysts, although it remains challenging at the atomic level. In this work, we have demonstrated that the planar defects, such as stacking faults, could drive electrocatalysis of CO₂-to-C₂H₄ conversion with higher selectivity and productivity than Cu(100) facets at the intermediate potential region. We prepared the unique right bipyramidal Cu nanocrystals containing a combination of (100) facets and a set of parallel planar defects, which delivered 67% Faradic efficiency (FE) of C₂H₄ and partial current density of 217 mA cm^-2 at -0.63 V vs. RHE. In contrast, Cu nanocubes with excusive (100) facets exhibited only 46% FE of C₂H₄ at the identical potential. Both ex situ CO temperature-programmed desorption and in situ Raman spectroscopy analysis implied that the stronger *CO adsorption on planar defect sites fosters CO generation kinetics, which contributes to a higher surface coverage of *CO and in turn an enhanced reaction rate of C-C coupling towards C₂₊ products, especially C₂H₄. Additionally, a 50-h durability test illustrated that defects are stabilized by *CO under CO₂RR conditions. Our results could provide an in-depth insight into the reactivity comparison between planar defects and Cu(100) facets, which guides in designing advanced catalysts for efficient CO₂-to-C₂H₄ conversion.