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

Abstract Copper (Cu) oxides hold great potential for electrochemical synthesis of multi‐carbon (C 2+ ) products from CO 2 reduction reaction (CO 2 RR), but a clear picture correlating chemical bond characteristics in pristine Cu oxides with inevitable reconstruction during CO 2 RR remains underexplored. Herein, we report our findings in the regulation of Cu─O bond polarizability in layered cuprates (Ln 2 CuO 4 , Ln = La, Pr, Nd, Sm, and Gd) by an A‐site rare‐earth modulation strategy, to promote surface reconstruction toward high‐efficiency C 2+ electrosynthesis. In particular, the optimized Pr 2 CuO 4 bulk material with largest bond polarizability exhibits the best performance, achieving a Faradaic efficiency of ∼80% for C 2+ products and a C 2+ 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/Pr 2 CuO 4 interface, function as dual active sites to improve * CO coverage and lower the energy barrier for C─C coupling, resulting in the enhanced C 2+ selectivity.