Surface Structure Reformulation from CuO to Cu/Cu(OH)2 for Highly Efficient Nitrate Reduction to Ammonia

• Published in: Advanced science Vol. 11; no. 38; pp. e2404194 - n/a
• Main Authors: Li, Jin, Jiang, Qiuling, Xing, Xiujing, Sun, Cuilian, Wang, Ying, Wu, Zhijian, Xiong, Wei, Li, Hao
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01-10-2024; John Wiley and Sons Inc; Wiley
• Subjects: Acids; Adsorption; Agricultural production; Ammonia; Carbon; Catalysis; Chemical bonds; Copper; Crystal structure; Cu(OH)2, CuO; Electrodes; Electrons; Energy consumption; Fourier transforms; Hydrogen; Morphology; Nitrates; Nitrogen; NO3RR; Spectrum analysis; structural and phase changes; Temperature; Cu(OH)2, CuO; NO3RR; structural and phase changes
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202404194

Electrochemical conversion of nitrate (NO3−) to ammonia (NH3) is a potential way to produce green NH3 and remediate the nitrogen cycle. In this paper, an efficient catalyst of spherical CuO made by stacking small particles with oxygen‐rich vacancies is reported. The NH3 yield and Faraday efficiency are 15.53 mg h−1 mgcat−1 and 90.69%, respectively, in a neutral electrolyte at a voltage of ‐0.80 V (vs. reversible hydrogen electrode). The high activity of the electrodes results from changes in the phase and structure during electrochemical reduction. Structurally, there is a shift from a spherical structure with dense accumulation of small particles to a layered network structure with uniform distribution of small particles stacked on top of each other, thus exposing more active sites. Furthermore, in terms of phase, the electrode transitions from CuO to Cu/Cu(OH)2. Density functional theory calculations showed that Cu(OH)2 formation enhances NO3‐ adsorption. Meanwhile, the Cu(OH)2 can inhibit the competing hydrogen evolution reaction, while the formation of Cu (111) crystal surfaces facilitates the hydrogenation reaction. The synergistic effect between the two promotes the NO3‐ to NH3. Therefore, this study provides a new idea and direction for Cu‐based oxides in electrocatalytic NH3 production.
A high‐performance small particle stacked spherical CuO catalyst for NO3RR is developed. Benefiting from the Cu/Cu(OH)2 structure formed during the electrolytic reduction process, it has excellent NO3− reducing properties. Where Cu(OH)2 enhanced the adsorption of nitrate ions and the inhibition of the competitive HER reaction, and the presence of Cu facilitated the hydrogenation reaction.