Adv. Funct. Mater. - Defect-Enriched Cobalt-Based Coordination Polymers for Selective and Efficient Nitrate Electroreduction to Ammonia

Yidan Ding, Shouhan Zhang, Yunxia Liu, Yan Liu, Hui Zheng, Li Qing, Yuanhao Song, Ziwei Ma, Longsheng Zhang*, Tianxi Liu*

Adv. Funct. Mater. 2025, DOI: 10.1002/adfm.202422339

Electrocatalytic nitrate reduction to ammonia (NRA) offers an arousing route for converting widespread nitrate pollutant to ammonia under mild conditions. Among other NRA catalysts, single-atom catalyst (SAC) has emerged as a promising candidate due to its numerous advantages such as maximum metal-atom-utilization efficiency, homogeneous and tailorable active sites, which still encounters a formidable challenge to accelerate the NRA kinetics and simultaneously suppress the competitive hydrogen evolution reaction, especially when operated in the electrolytes with low concentration nitrate. Herein, a general strategy is reported to prepare defect-enriched coordination polymer catalysts featuring with well-defined and unsaturated single-atom metal sites, which can exhibit exceptional NRA performance even at low nitrate concentration and surpass other reported SACs toward NRA catalysis. Taking cobalt (Co) as an example, defect-enriched Co-based coordination polymers (d-CoCP) and its counterpart CoCP without defects are investigated as the proof-of-concept study. Both the experimental and theoretical results elucidate that the elaborately-engineered defects in the d-CoCP can markedly decrease the thermodynamic barrier for reducing *NO to *HNO at the rate-limiting step along NRA pathway, thus accelerating the adsorption of nitrate and promoting the NRA kinetics.

Link: https://doi.org/10.1002/adfm.202422339