Delocalization State-Stabilized Znδ+ Active Sites for Highly Selective and Durable CO2 Electroreduction

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-10, p.e2406604
• Main Authors: Liu, Qian-Wen, He, Bing-Ling, Zheng, De-Sheng, Zhou, Xue-Qin, Zhang, Xin, Huang, Jian-Mei, Wang, Yu, Lai, Wen-Chuan, Gu, Zhi-Yuan
• Format: Article
• Language: English
• ISSN: 1613-6829; 1613-6829
• DOI: 10.1002/smll.202406604

Zinc (Zn)-based materials are cost-effective and promising single-metal catalysts for CO2 electroreduction to CO but is still challenged by low selectivity and long-term stability. Undercoordinated Zn (Znδ+) 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 Znδ+, resulting in the decline of CO efficiency over prolonged operation. Herein, a Zn cyanamide (ZnNCN) catalyst is constructed for highly selective and durable CO2 electroreduction, wherein the delocalized Zn d-electrons and resonant structure of cyanamide ligand prevent the self-reduction of ZnNCN and maintain Znδ+ sites under cathodic conditions. The mechanism studies based on density functional theory and operando spectroscopies indicate that delocalized Znδ+ site can stabilize the key *COOH intermediate through hard-soft acid-base theory, therefore thermodynamically promoting CO2-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 CO2 reduction catalysts, this work also offers insights into understanding the structure-function sensitivity and controlling dynamic active sites.Zinc (Zn)-based materials are cost-effective and promising single-metal catalysts for CO2 electroreduction to CO but is still challenged by low selectivity and long-term stability. Undercoordinated Zn (Znδ+) 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 Znδ+, resulting in the decline of CO efficiency over prolonged operation. Herein, a Zn cyanamide (ZnNCN) catalyst is constructed for highly selective and durable CO2 electroreduction, wherein the delocalized Zn d-electrons and resonant structure of cyanamide ligand prevent the self-reduction of ZnNCN and maintain Znδ+ sites under cathodic conditions. The mechanism studies based on density functional theory and operando spectroscopies indicate that delocalized Znδ+ site can stabilize the key *COOH intermediate through hard-soft acid-base theory, therefore thermodynamically promoting CO2-to-CO conversion. Consequently, ZnNCN delivers a CO Faradaic