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

Zinc (Zn)-based materials are cost-effective and promising single-metal catalysts for CO electroreduction to CO but is still challenged by low selectivity and long-term stability. Undercoordinated Zn (Zn) 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, resulting in the decline of CO efficiency over prolonged operation. Herein, a Zn cyanamide (ZnNCN) catalyst is constructed for highly selective and durable CO electroreduction, wherein the delocalized Zn d-electrons and resonant structure of cyanamide ligand prevent the self-reduction of ZnNCN and maintain Zn sites under cathodic conditions. The mechanism studies based on density functional theory and operando spectroscopies indicate that delocalized Zn site can stabilize the key COOH intermediate through hard-soft acid-base theory, therefore thermodynamically promoting CO-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 reduction catalysts, this work also offers insights into understanding the structure-function sensitivity and controlling dynamic active sites.