Halogen-induced planar defects in Cu catalysts for ammonia electrosynthesis at an ampere-level current density

作者：Wang, Yan; Xia, Shuai; Zhang, Jianfang^*; Ummireddi, Ashok Kumar; Li, Zhengyuan; Yuan, Xu; Yu, Cuiping; Zhang, Yong; Wu, Jingjie^*; Wu, Yucheng^*

来源：Materials Chemistry Frontiers, 2023, 7(15): 3093-3101.

DOI：10.1039/d3qm00114h

• ELECTROCATALYTIC NITRATE REDUCTION
• NITROGEN REDUCTION
• CO2 REDUCTION
• COPPER
• ELECTROREDUCTION
• BOUNDARY

The electrocatalytic nitrate reduction reaction (NO3-RR) provides an effective route for removing NO3- from wastewater and converting it to valuable ammonia (NH3). Here, we describe the halogen-incorporated Cu (Cu-X) catalysts derived from the in situ reduction of CuO nanoparticles in electrocatalytic NO3-RR. Electrochemical reconstruction induces various defect active sites in Cu-X catalysts by doping different halogens. The coexisted planar twin boundary (TB) and stacking fault (SF) defects in the Cu-F electrode possess higher activity than sole SF defects in Cu-Cl and grain boundary (GB) defects in both Cu-Br and Cu-I electrodes. The electrochemical in situ spectroscopic analysis reveals that the simultaneous TB and SF defects in the Cu-F electrode enhance the adsorption capacity of reaction intermediates and improve the conversion efficiency of NO3- to NH3. An ampere-level current density of NH3 synthesis is achieved on the Cu-F electrode with a high yield rate of 5.22 mmol h(-1) cm(-2), faradaic efficiency of 96.2%, and stability over 24 h. This work provides a promising strategy to finely modulate active sites in the Cu catalyst for high-efficiency NH3 synthesis from NO3-RR.