Delocalization State-Stabilized Zn δ+ Active Sites for Highly Selective and Durable CO 2 Electroreduction.

Zinc (Zn)-based materials are cost-effective and promising single-metal catalysts for CO ₂ electroreduction to CO but is still challenged by low selectivity and long-term stability. Undercoordinated Zn (Zn ^δ+ ) sites have been demonstrated to be powerful active centers with appropriate ^* COOH affinity for efficient CO production However, electrochemical reduction conditions generally cause the inevitable reduction of Zn ^δ+ , resulting in the decline of CO efficiency over prolonged operation. Herein, a Zn cyanamide (ZnNCN) catalyst is constructed for highly selective and durable CO ₂ electroreduction, wherein the delocalized Zn d-electrons and resonant structure of cyanamide ligand prevent the self-reduction of ZnNCN and maintain Zn ^δ+ sites under cathodic conditions. The mechanism studies based on density functional theory and operando spectroscopies indicate that delocalized Zn ^δ+ site can stabilize the key ^* COOH intermediate through hard-soft acid-base theory, therefore thermodynamically promoting CO ₂ -to-CO conversion. Consequently, ZnNCN delivers a CO Faradaic efficiency (FE) of up to 93.9% and further exhibits a remarkable stability lifespan of 96 h, representing a significant advancement in developing robust Zn-based electrocatalysts. Beyond expanding the variety of CO ₂ reduction catalysts, this work also offers insights into understanding the structure-function sensitivity and controlling dynamic active sites.
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