Hunan University reports a strategy for the electrochemical synthesis of formamide from CO2 and amin

 Professor Zou Yuqin from Hunan University published a research paper titled "Electrochemical synthesis of formamide by C-N coupling with amine and CO2 with a high Faradaic efficiency of 37.5%" in the journal Chem. This research reports an electrochemical strategy for directly converting carbon dioxide and dimethylamine into dimethylformamide (DMF) under ambient conditions. Through the rational design of the catalyst, a green path for the efficient electrochemical C-N coupling of CO2 reduction to synthesize DMF was achieved. This work provides guidance for the sustainable synthesis of high-value organic nitrogen compounds from CO2. 

The corresponding author of the paper is Professor Zou Yuqin, and the first author is Dr. Fan Yun. 

The sustainable synthesis of high-value products from CO2 molecules is a promising electrochemical strategy for the production of fuels and other fine chemicals. However, the products that can be constructed using only CO2 and H2O as reactants are very limited. Therefore, there is an urgent need to expand the range of CO2 electroreduction products to meet the huge market demand. Organic nitrogen compounds are widely used in pesticides, plastics, and polymers, and the research on converting nitrogen- and carbon-containing small molecules into organic nitrogen compounds has received increasing attention. Directly using CO2 as the carbon source for these reactions has the obvious advantage of simplifying the process and achieving clean conversion. Among all amide compounds, N,N-dimethylformamide (DMF) is known as a universal solvent due to its high chemical activity and wide liquid range. Currently, the production of DMF mainly relies on the synthesis of methyl formate (C2H4O2) from CO and CH3OH, followed by coupling with dimethylamine at high temperatures (323-473 K) and pressures (0.5-11.0 MPa). This process is energy-intensive and generates a large amount of pollutants. 

In this work, Professor Zou Yuqin's team adopted an electrocatalytic strategy to achieve the electrochemical C-N coupling of CO2 and dimethylamine to synthesize DMF under ambient conditions using a Cu-based catalyst. To further improve the synthesis efficiency of the coupling product, Cu vacancies were first constructed to promote the adsorption of CO2 on the electrode surface, which then spontaneously coupled with dimethylamine to form the *OCNH(CH3)2O intermediate. Further, palladium nanoparticles were introduced on the electrode surface to accelerate the electrochemical hydrogenation process. In a flow-type electrolytic cell, the Faradaic efficiency of DMF could reach up to 37.5%, and the maximum yield was 385 mmol·h-1·gcat.-1. In-situ characterization and theoretical calculations revealed the reaction pathway and mechanism of C-N coupling. This work, through the electrochemical C-N coupling of organic amines with CO2 to synthesize formamide, is expected to be extended to the synthesis of other amides in the future. 

Figure 1: Schematic diagram of traditional thermochemical and electrochemical strategies for the production of DMF. 

Figure 2: Physical and chemical characterization of Cu, Cu-VCu and Pd/Cu-VCu catalysts. 

Figure 3: Electrochemical performance testing and characterization. 

Figure 4: In-situ Raman and in-situ infrared spectroscopy studies on the regulation of reaction intermediates. 

Figure 5: Density functional theory calculations of reaction pathways. 

This work utilized electrocatalytic technology and Cu-based catalysts under environmental conditions to achieve the sustainable electrochemical C-N coupling of CO2 and dimethylamine to synthesize DMF. The synthesis of nitrogen-containing organic compounds such as amides from carbon dioxide molecules expanded the range of CO2 electroreduction products, opening up a more valuable transformation pathway for the conversion of CO2.