Researchers at Johannes Gutenberg University Mainz (JGU) have now presented a method for electrocatalytically converting carbon dioxide into ethanol, which is then available as a sustainable raw material for chemical applications.

According to Professor Carsten Streb from the JGU Department of Chemistry, the conversion technique, which has so far been carried out on a laboratory scale, could also be realized on a larger scale. The research results have been published in ACS Catalysis.

The electrochemical conversion of CO₂ to multicarbon products, such as ethanol, would be an ideal way to obtain high energy density fuels and valuable chemical raw materials, while at the same time using CO₂ as a precursor and thus removing it from the atmosphere to a certain extent.

To achieve this, we require suitable catalysts capable of this conversion with high selectivity so that we obtain a high yield of the desired product, which—in our case—is ethanol.

—Professor Streb

The research team designed an electrode coated with a black powder containing cobalt and copper in precisely dosed quantities. The two metals also have to sit in very specific positions on the electrode.

The cobalt initially breaks the CO₂ bonds to produce carbon monoxide, while the copper then carries out the reaction to ethanol. However, said Streb, this only works if cobalt and copper are close to each other on the electrode.

Currently, the selectivity of the process is 80%—i.e., 80% of the starting material is converted to ethanol—the best result achieved in research to date. Dr. Soressa Abera Chala played a key role in optimizing the results. He is lead author of the paper and came as a postdoc with a Humboldt Research Fellowship to Mainz from Ethiopia. Two of the co-authors, Dr. Rongji Liu and Dr. Ekemena Oseghe, are also working in Streb’s group as fellows of the Alexander von Humboldt Foundation.

The team is currently working on improving the yield of the process to 90 to 95%. A catalyst that achieves 100% selectivity would be desirable so that no other substances, apart from ethanol alone, would remain on completion of the process.

Resources

• Selective Electroreduction of CO₂ to Ethanol via Cobalt–Copper Tandem Catalysts; Soressa Abera Chala, Rongji Liu, Ekemena O. Oseghe, Simon T. Clausing, Christopher Kampf, Joachim Bansmann, Adam H. Clark, Yazhou Zhou, Ingo Lieberwirth, Johannes Biskupek, Ute Kaiser, and Carsten Streb ACS Catalysis 2024 14 (20), 15553-15564 doi: 10.1021/acscatal.4c05286