Efficient nitrate electroreduction over Mn-doped Cu catalyst via regulating N-containing intermediates adsorption configuration

This study is led by Prof. Buxing Han and Prof. Xiaofu Sun (Institute of Chemistry, Chinese Academy of Sciences). The experiments were performed by construct Mn-doped Cu catalysts for electrochemical NO₃^--to-NH₃ in a neutral electrolyte at low NO₃^- concentration.

Interestingly, the doping of Mn into Cu resulted in exceptional performance, achieving a FE of 95.8% and an NH₃ yield rate of 0.91 mol g^-1 h^-1 at -0.6 V vs. RHE in a neutral electrolyte at low NO₃^- concentration. Detailed experimental studies and theoretical calculations revealed that the Mn dopant enhanced the kinetic rate of NO₂^--to-NH₃ and induced a distinct configuration of *NO. This alteration decreased the energy barrier of *NO-to-*NOH, consequently promoting the conversion of NO₃^--to-NH₃.   

“NO₃^- prevalent in industrial and agricultural wastewater, pose significant threats to human health and ecological balance, particularly due to their potential incomplete conversion into cancerogenic nitrites NO₂^-. Addressing this, the electrochemical reduction of NO₃^- to NH₃ stands as a promising avenue characterized by its potential economic and environmental advantages, offering a solution to water pollution and nitrogen cycle imbalance. To enhance the efficiency of converting NO₃^- to NH₃, it becomes imperative to develop Cu-based catalysts capable of precisely regulating the interactions between reactive intermediates and active sites, thereby modulating the kinetic processes involved. The introduction of modifier elements into copper induces the shifts in electron cloud density and d-band center, thereby governing the adsorption strength of intermediates. Besides, the introduction of elements with different oxygen affinities also affects the *NO configurations on the catalyst surface, which in turn affects the pathway and selectivity of nitrate reduction. Therefore, the introduction of moderate modifier elements aims to optimize the interaction between intermediates and active sites, which shows a reasonable prospect to enhance the overall efficiency of nitrate electroreduction.” Sun says.

This work not only presents the way of adjusting the adsorption configuration of intermediates to promote the conversion of NO₃^--to-NH₃, but also provides an in-depth understanding of the mechanism. We believe that it may inspire the design of novel catalyst with high-efficiency for NH₃ synthesis.

See the article:

Efficient Nitrate Electroreduction over Mn-doped Cu Catalyst via Regulating N-containing Intermediates Adsorption Configuration

https://doi.org/10.1007/s11426-024-2040-8