Team of BIT achieved significant progress in electrocatalytic nitric acid reduction to Ammonia
News Source: School of Chemistry and Chemical Engineering Ji Xueyang
Editor: Duan Kailong
Translator: Aram Kim, BIT News Agency
Recently, the team led by Professor Tao Jun from the School of Chemistry and Chemical Engineering, Beijing Institute of Technology, has made great progress in the electrocatalytic nitrate reduction to Ammonia. The result of the relevant research which is subjected “Identification of dynamic active sites among Cu species derived from MOFs@CuPc for electrocatalytic nitrate reduction reaction to ammonia” is published in the internationally renowned journal Nano-Micro Letters （DOI：10.1007/s40820-023-01091-9）. BIT is the first communication unit for this work, and Professor Tao Jun and Dr. Liu Xinghui from Sungkyunkwan University, South Korea, are the co-corresponding authors, and doctoral student Ji Xueyang is the first author of the paper. This article also received technical support from the team of Shao Ruiwen, an associate researcher at the Institute of Engineering Medicine, BIT, in the aspect of double spherical aberration correction scanning transmission electron microscopy.
The direct electrochemical nitrate reduction reaction (NITRR) is a promising approach to alleviate the unbalanced nitrogen cycle and realize the electrosynthesis of NH3. However, the restructuration of high-activity Cu-based electrocatalysts during the NITRR reaction hinders the identification of dynamic active sites and the in-depth study of the catalytic mechanism. In general, transition metal atoms are prone to migrate and aggregate into metal nanoclusters and/or nanoparticles during high-temperature pyrolysis, which seriously affects the synthesis of high-loaded metal single-atom catalysts. Therefore, exploring the dual driving behavior of Cu species catalyst loading and reaction potential in the process of electrocatalytic NH3 generation is the key to reveal the origin of electrocatalytic NITRR activity.
The team built on the customized synthesis of MOFs catalysts to improve the performance of catalytic reactions based on the previous research work on metal-organic frameworks (MOFs) (Catal. Sci. Technol. 2020, 10, 5048–5059; Mater. Chem. Front. 2021, 5, 7796–7807; Nano Res. 2022, 15 , 6045–6053). Herein, Cu species (single-atom, clusters, and nanoparticles) catalysts anchored on N-doped TiO2/C were synthesized through a pre-anchoring and post-pyrolysis strategy. The results show that the remodeling behavior of Cu components during electrocatalytic NITRR is related to the Cu loading and the reaction potential. Specifically, it is easier to convert Cu single-atom sites into Cu clusters and nanoparticles through potential-driven aggregation at higher Cu loadings and negative reaction potentials, while part of reconstituted Cu clusters and nanoparticles under ambient conditions Cu clusters and nanoparticles reversibly turn into Cu single atoms through oxidation-driven redispersion. The reconstructed CuN4&Cu4 structure at −0.75 V vs. RHE potential can achieve an NH3 production rate of 88.2 mmol h−1 gcata−1 and an FE of ~94.3%.
Fig.1 Coordination numbers of Cu–N and Cu–Cu in Cu species catalysts vary with potential and the mechanism of reconstitution and redispersion
Density functional theory (DFT) calculations indicate that the strong interaction between CuN4 and Cu clusters in the CuN4&Cu4 structure enhances the adsorption of reaction substrates and intermediates by shifting up the d-band center of single-site Cu. In addition, the Cu clusters improve the charge distribution and electronic structure of Cu at a single point, and accelerate the rapid conversion of the reaction intermediate *NH2OH to*NH2, and finally achieve the optimal electrocatalytic NH3 production performance on the CuN4&Cu4 structure.
Fig.2 Theoretical calculation results of different Cu structures and the mechanism of NITRR process
This research was supported by the National Natural Science Foundation of China (92061106 and 21971016). At the same time, the technical support provided by analysis and testing center of BIT and the staff of Beijing Synchrotron Radiation Facility is appreciated.
Article link: https://link.springer.com/article/10.1007/s40820-023-01091-9
Tao Jun: Distinguished Professor of School of Chemistry and Chemical Engineering, BIT, winner of the National Science Fund for Distinguished Young Scholars. He is mainly engaged in the research of magnetic, optical, dielectric, ferroelectric and catalytic properties of molecular-based materials, and has published a number of academic papers in Chem. Soc. Rev., Nat. Commun., J. Am. Chem. Soc., Angew. Chem., Int. Ed. and so on.
Liu Xinghui (co-corresponding author): He obtained D. degree in sicence from 2021, Sungkyunkwan University, South Korea, in 2021, and is currently doing postdoctoral research in the team of Professor Zhi Chunyi of City University of Hong Kong. He is now committed to the design of new materials (new structures) and related research on energy conversion with advanced computational simulation, and has published many academic papers in Angew. Chem. Int. Ed., Nat. Commun., Matter, Chem. Sci., ACS Nano, ACS Catal., Nano-Micro Letters and other journals.