Rare‐Earth Regulated Bond Polarizability in Layered Cuprates for Promoted Surface Reconstruction Toward C ₂₊ Electrosynthesis

Copper (Cu) oxides hold great potential for electrochemical synthesis of multi-carbon (C₂₊) products from CO₂ reduction reaction (CO₂RR), but a clear picture correlating chemical bond characteristics in pristine Cu oxides with inevitable reconstruction during CO₂RR remains underexplored. Herein, we report our findings in the regulation of Cu─O bond polarizability in layered cuprates (Ln₂CuO₄, Ln = La, Pr, Nd, Sm, and Gd) by an A-site rare-earth modulation strategy, to promote surface reconstruction toward high-efficiency C₂₊ electrosynthesis. In particular, the optimized Pr₂CuO₄ bulk material with largest bond polarizability exhibits the best performance, achieving a Faradaic efficiency of ∼80% for C₂₊ products and a C₂₊ partial current density of 376.2 mA cm^-2 at -1.7 V versus RHE as well as maintaining robust durability at 200 mA cm^-2 in a membrane electrode assembly. Experimental and theoretical results reveal that larger Cu─O bond polarizability, characterized as increased bond length and decreased valence state, accelerates the Cu-O bond breaking that can lead to the formation of ultrasmall, highly dispersed, and strained Cu nanoparticles. These reconstructed metallic Cu particles, together with Cu/Pr₂CuO₄ interface, function as dual active sites to improve ^*CO coverage and lower the energy barrier for C─C coupling, resulting in the enhanced C₂₊ selectivity.