Enhanced electrochemical nitrate reduction on copper nitride with moderate intermediates adsorption

• Published in: Journal of colloid and interface science 2024-09, Vol.670, p.798-807
• Main Authors: Wei, Jinshan, Ye, Gan, Lin, Hexing, Li, Zhiming, Zhou, Ji, Li, Ya-yun
• Format: Article
• Language: English
• Subjects: adsorption; ammonia; Ammonia synthesis; ammonium fertilizers; catalysts; Copper nitride (Cu3N); density functional theory; Electrocatalysis; electrochemistry; energy; groundwater; Nitrate reduction; nitrates; nitrides; Nitrogen vacancy; risk; wastewater treatment; Water treatment
• ISSN: 0021-9797; 1095-7103; 1095-7103
• DOI: 10.1016/j.jcis.2024.05.084

[Display omitted] •Newly synthesized Cu3N catalyst was employed for electrocatalytic nitrate reduction and ammonia production.•The strategy of balancing *H2O and *NO3 intermediates adsorption for enhanced NO3RR was highlighted.•In-situ and ex-situ analysis verify the potential driven reconstruction and rehabilitation of Cu3N. Nitrate in surface and underground water caused systematic risk to the ecological environment. The electrochemically reduction of nitrate into ammonia (NO3RR), offering a sustainable route for nitrate containing wastewater treatment and ammonia fertilizer conversion. Exploration of catalyst with improved catalytic activity with lower energy barriers is still challenging. Here, we report a copper nitride (Cu3N) catalyst with moderate *NOx and *H2O intermediates adsorptions showed enhanced NO3RR performance. Density functional theory calculations reveals that the unique electronic structure of Cu3N provides efficient active sites for NO3RR, thus enabled balanced adsorption of *NO3 and *H2O (ΔE descriptor), sufficient active hydrogen, and moderate intermediate (*NO3 → HNO3, *NH2→*NH3) adsorption energy. Notably, the in-situ analysis technology revealed potential-driven reconstruction and rehabilitation of Cu3N, forming possible nitrogen vacancy, thus implied for better mechanism understanding. The NO3RR activity of Cu3N surpasses that of most recent catalysts and demonstrates superior stability and implies the application for NH4+ fertilizer recovery, which maintaining an NH3 Faradaic efficiency of 93.1 % and high yield rate of 2.9 mg cm2h−1 at −0.6 V versus RHE. These findings broaden the application scenarios of Cu3N catalyst for ammonia synthesis and provide strategy on improving NO3RR performance.