Conjugated Coordination Polymers with Well‐Defined Single‐Atom Metal Sites for Efficient Nitrogen Electroreduction to Ammonia

Abstract Electrocatalytic nitrogen reduction reaction (NRR) provides a sustainable and environment‐friendly approach for ammonia (NH 3 ) electrosynthesis under ambient conditions, which unfortunately encounters sluggish reaction kinetics for dissociating N 2 reactants, resulting in unsatisfied Faradaic efficiency and NH 3 yield rate. Developing efficient NRR electrocatalysts is a prerequisite, wherein single‐atom catalyst (SAC) has profoundly emerged as a promising candidate owing to its arousing advantages such as well‐defined active sites and maximum metal‐utilization efficiency. Nevertheless, it is desired yet challenging to increase the single‐atom metal content and simultaneously achieve controllable regulation of the coordination structures of single‐atom metal sites. Herein, a high‐metal‐density conjugated coordination polymeric (CCP) catalyst featuring abundant single‐atom metal sites is developed with precisely‐tailored local coordination structures, which exhibit exceptional NRR performance toward efficient and selective NH 3 electrosynthesis. Taking nickel (Ni) as an example, NiN 4 ‐ and NiO 4 ‐ centered CCP catalysts with analogous structures are investigated as proof‐of‐concept studies. Experimental and theoretical studies suggest that the resulting NiN 4 ‐centered catalyst with upward tuned Ni 3d‐band center can appreciably enhance N 2 absorption/dissociation kinetics relative to the NiO 4 ‐centered catalyst, leading to its improved NRR performance.