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.