Boosting Electrochemical Ammonia Synthesis via NOx Reduction over Sulfur‐Doped Copper Oxide Nanoneedle Arrays

• Published in: Advanced energy materials Vol. 14; no. 30
• Main Authors: Zhang, Taisong, Lv, Jiangnan, Yang, Ruixia, Yan, Zhi, Sun, Xiaoting, Xu, Xiaohong, Liu, Yang
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 09.08.2024
• Subjects: Ammonia; ammonia synthesis; Arrays; Catalysts; Chemical reactions; Chemical reduction; Chemical synthesis; Copper oxides; Density functional theory; Dopants; doping effect; electrocatalysis; metal sulfide; nitrate reduction; Nitrates; Nitrogen dioxide; Sulfur
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202400790

The electrochemical NOx reduction reactions, involving nitrate and nitrite reduction reactions (NO3−RR and NO2−RR), have emerged as promising approaches for both NO3− and NO2− removal, and ammonium (NH3) synthesis under ambient conditions. However, the incorporation and stabilization of sulfur dopants in the catalysts for efficient NOx reduction are rarely explored, leading to an unclear effect of sulfur on the NOx reduction mechanism. Herein, sulfur‐doped Cu2O (S‐Cu2O) nanoneedle arrays via in situ electrochemical treatment are synthesized. The S‐Cu2O catalyst possesses excellent durability and selectivity for NH3 over a wide range of potentials in NO3−RR, attaining a maximum NH3 Faradaic efficiency of 94% at −0.6 VRHE and a maximum NH3 yield as high as 1.06 mmol h−1 cm−2. In NO3−RR, the sulfur dopant can accelerate the step from NO2− to NH3, contributing superior performance in NO2−RR and assembled Zn−NO2− battery device. Density functional theory (DFT) calculations reveal that the presence of sulfur can enhance the initial step of *NO3 adsorption, lower the reaction barriers for the formation of *NHO intermediate, and activate the H2O dissociation process. The work sheds light on the role of sulfur in enhancing electrocatalytic performance and provides a unique perspective for understanding the NOx reduction mechanism. Electrocatalytic nitrate and nitrite reduction reaction to ammonia (NH3) is of great significance in environmental issues and industry feedstocks. Sulfur‐doped Cu2O shows the potential to efficiently convert NO3− and NO2− to NH3 with high selectivity and stability. Combining the electrochemical performances, in situ spectroscopic characterizations, and theoretical calculations, it is revealed that sulfur dopant can promote the NO3− adsorption and the NO2− to NH3 steps.