Accelerating Industrial‐Level NO3− Electroreduction to Ammonia on Cu Grain Boundary Sites via Heteroatom Doping Strategy

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2023-06, Vol.19 (26), p.e2302295-n/a
• Main Authors: Wang, Yan, Xia, Shuai, Cai, Rui, Zhang, Jianfang, Wang, Jiarui, Yu, Cuiping, Cui, Jiewu, Zhang, Yong, Wu, Jingjie, Yang, Shize, Tan, Hark Hoe, Wu, Yucheng
• Format: Article
• Language: English
• Subjects: Ammonia; Catalysts; Chemical reduction; Chemical synthesis; Copper; Density functional theory; Doping; electrocatalytic nitrate reduction; Electrodes; Electrowinning; Fourier transforms; Grain boundaries; grain boundary sites; hydrogen evolution reaction (HER) suppression; Hydrogen evolution reactions; Infrared reflection; Nanotechnology; NH3 synthesis; Nitrates; Reaction intermediates; Sn doping
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202302295

Although the electrocatalytic nitrate reduction reaction (NO3−RR) is an attractive NH3 synthesis route, it suffers from low yield due to the lack of efficient catalysts. Here, this work reports a novel grain boundary (GB)‐rich Sn‐Cu catalyst, derived from in situ electroreduction of Sn‐doped CuO nanoflower, for effectively electrochemical converting NO3− to NH3. The optimized Sn1%‐Cu electrode achieves a high NH3 yield rate of 1.98 mmol h−1 cm−2 with an industrial‐level current density of −425 mA cm−2 at −0.55 V versus a reversible hydrogen electrode (RHE) and a maximum Faradaic efficiency of 98.2% at −0.51 V versus RHE, outperforming the pure Cu electrode. In situ Raman and attenuated total reflection Fourier transform infrared spectroscopies reveal the reaction pathway of NO3−RR to NH3 by monitoring the adsorption property of reaction intermediates. Density functional theory calculations clarify that the high‐density GB active sites and the competitive hydrogen evolution reaction (HER) suppression induced by Sn doping synergistically promote highly active and selective NH3 synthesis from NO3−RR. This work paves an avenue for efficient NH3 synthesis over Cu catalyst by in situ reconstruction of GB sites with heteroatom doping. The incorporation of appropriate Sn into Cu catalyst can induce abundant grain boundary active sites and suppress the hydrogen evolution reaction, which cooperatively promotes electrocatalytic NO3− reduction to NH3 synthesis with enhanced activity and selectivity.