Co <sub>1</sub> Zn Single‐Atom Alloy Boosts Active Hydrogen Spillover for Highly Efficient Electrosynthesis of Ammonia Over 2 A cm <sup>−2</sup> Current Density
Zhipeng Chen, Gen Liu, Yusi Zhao, Yan Yan, Qingping Ke, Chao Wan, Zhirong Zhang, Jiaxin Yuan, Hongliang Li, Mingkai Liu, Jie Zeng
Abstract
Abstract Electroreduction of nitrate to ammonia reaction (NO 3 RR) involves a series of hydrogenation steps involving nitrate‐derived intermediates. Consequently, accelerating the provision of active hydrogen is expected to enhance the reaction kinetics. In this work, we report a Co 1 Zn single‐atom alloy (SAA) catalyst that exhibits a pronounced hydrogen spillover effect. By virtue of this spillover phenomenon, the Co 1 Zn SAA nanosheets (Co 1 Zn NSs) achieve nitrate electroreduction at ampere‐level current densities. Specifically, Co 1 Zn NSs deliver a high current density of 2.4 A cm −2 (corresponding to an ammonia yield rate of 204.5 mg h −1 cm −2 ) with a Faradaic efficiency of 98.7% for ammonia production, which is approximately 2.5‐fold higher than that obtained with Zn nanosheets lacking hydrogen spillover effect. Moreover, Co 1 Zn NSs demonstrate a great application potential in Zn−NO 3 − rechargeable battery. In situ electrochemical impedance spectroscopy (EIS), in situ electron paramagnetic resonance spectroscopy (EPR), and density functional theory (DFT) calculations reveal that the isolated Co atoms in Co 1 Zn NSs served as a “hydrogen pump” for hydrogen spillover during NO 3 RR, thereby increasing the coverage of active hydrogen on the catalyst surface and lowering the energy barrier of the rate‐determining step of NO 3 RR, and finally markedly enhanced the catalytic performance.