Tailored Reconstruction of Polycrystalline CuO Nanorods Promotes C─C Coupling in CO2 Electroreduction

Designing structurally robust and functionally active catalysts is essential for advancing CO2 electroreduction toward multicarbon (C2+) products. Here, a crystallinity‐engineering strategy is reported to regulate the reconstruction behavior of CuO nanorod catalysts and stabilize critical surface features that promote C─C coupling. Specifically, low‐polycrystalline CuO (LP‐CuO) nanorods undergo directional reconstruction into rod‐like metallic Cu structures under electrochemical conditions, effectively preserving surface hydroxides and partial Cu+ oxidation states. In‐situ/operando X‐ray absorption spectroscopy confirms the retention of Cu(OH)2 species in LP‐CuO, while surface‐enhanced infrared absorption spectroscopy reveals the generation of abundant C2+ intermediates and a blueshift in interfacial water vibrations, indicating increased free water and enhanced proton‐donor activity. This interplay between stabilized surface hydroxides and interfacial water dynamics enables efficient C─C coupling and selective C2+ production, achieving a partial current density of 984 mA cm−2. The findings provide fundamental insights into the structure–function relationship of Cu‐based catalysts and establish crystallinity modulation as a generalizable design principle for high‐performance and durable electrocatalysts in CO2 conversion technologies.