J. Mater. Chem. A - Spin-engineered Cu-Ni metallic aerogels for enhanced ethylamine electrosynthesis from acetonitrile

Honggang Huang, Feili Lai, Hui Fu, Yao Chen, Hanjun Li, Feng He, Zhenyu Wang, Nan Zhang,* Shuxing Bai*, Tianxi Liu*

Journal of Materials Chemistry A 2023, DOI: 10.1039/D2TA09019H

Ethylamine is one of the simplest amines, widely used in hydrogen storage devices, organic reactions, energy conversion and other fields. Among the raw materials for the synthesis of ethylamine, acetonitrile as a by-product of the Sohio process of acrylonitrile has attracted more and more attention because of its easy availability. In the process of acetonitrile reduction reaction, due to the nucleophilic property of the intermediate of imine, secondary amine and tertiary amine will continue to be generated from the reaction of primary amine. Therefore, the product is a mixture of ethylamine, diethylamine and triethylamine, resulting in a reduction in the selectivity of primary amine. The strategies for improving the selectivity of primary amine reported so far are expensive and complex. It is of great significance to seek a green and economic improvement strategy.

Recently, Professor Liu Tianxi group from the School of Chemistry and Materials Engineering of Jiangnan University prepared a series of spin effect Cu-Ni metallic aerogels (MAs) with controllable composition by salt-gel method and freeze-drying, which are used for the electroreduction of acetonitrile to synthesize ethylamine. Due to the best d-orbital electron filling, Cu₃Ni₁ MAs showed the highest selectivity and yield of ethylamine for 98.01% and 173.2 μmol h^-1 respectively at -0.65 V_RHE, and exhibited 95.49% ethylamine Faraday efficiency at -0.45 V_RHE, which was better than Cu₃Ni₁ nanoparticles (NPs) (79.83%, 105.7 μmol h^-1 and 81.86%). In addition, Cu₃Ni₁ MAs showed 200.9 μmol h^-1 ethylamine yield under the flow cell of commercialized scale. Based on in-situ Raman and density functional theory (DFT) calculations, the unique structure and high spin state of Cu₃Ni₁ MAs optimized the adsorption of acetonitrile and imine intermediates during the acetonitrile reduction reaction (ARR), prevented the reaction between imine intermediates and free ethylamine molecules, and enhanced the selectivity and yield of ethylamine while protecting the primary amine. Current work shows that spin engineering plays an important role in improving the performance of ARR and provides a new strategy for creating efficient ARR electrocatalysts.

The first author of this article is Huang Honggang, a graduate student of the College of Chemical Engineering, and the corresponding authors are Professor Liu Tianxi, Assistant Professor Zhang Nan and Professor Bai Shuxing.

Article link: https://pubs.rsc.org/en/content/articlelanding/2023/ta/d2ta09019h

Morphology and structure characterization of Cu₃Ni₁ MAs