Enriched bicarbonate electrolytes show promise in combatting CO2 and the greenhouse effect

CO₂ER, the electrocatalytic reduction of carbon dioxide (CO₂), offers an ideal route for mitigating the greenhouse effect and achieving green CO₂ cycling. In recent years, most studies on CO₂ER have focused on the intrinsic performance of the catalysts.

While bicarbonate - an electrolyte or negatively-charged ion that is used by the body to help maintain its pH balance - is commonly used in CO₂ER, a group of researchers from China set out to explore its role and behaviour in more detail. Their results have been published in the KeAi journal Fundamental Research.

According to the paper’s corresponding author, Jinlong Gong, a professor in the School of Chemical Engineering and Technology at Tianjin University: “Bicarbonate, as a common electrolyte anion, can enhance CO₂ER activity via its rapid equilibrium exchange with dissolved CO₂. We found that higher concentrations of bicarbonate in the electrolyte provided higher energy efficiency.”

Dr. Wanyu Deng, the lead author of the paper, adds: “The new knowledge gained in this work guides the direct electroreduction of bicarbonate and provides valuable insights into CO₂ER with high-concentration electrolytes. This finding is expected to help save abundant energy in the CO₂ER process and can pave the way for advancing the progress of CO₂ER towards commercialisation.”

Through in-situ experimental observations, the team discovered an accumulation of negatively-charged bicarbonate anions in the vicinity of the electrode surface. The enriched bicarbonate anions converted to CO₂ to provide reactants. In addition, the local concentration of bicarbonate anions was controlled by both the bulk concentration of bicarbonate electrolyte and the cathodic potential. This discovery helped to explain the dependency of CO₂ER activity on the local bicarbonate concentration, where the limited cathodic potential caused a plateau in the CO₂ER activity.

Commenting on the plateau, Professor Gong says: “This hinders the use of high-concentration electrolytes to enhance activity. Further research is required to systematically explore the intrinsic relationship between CO₂ER activity and bicarbonate concentration to achieve better CO₂ER performance.”

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Contact the corresponding author: Jinlong Gong, jlgong@tju.edu.cn

The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 100 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).