Carbon dioxide (CO₂) emission has become a global problem that leads to climate change and greenhouse effect to the earth. Hence, efficient conversion of greenhouse gas CO₂ into value-added liquid fuels is one of significant ways to fix CO₂, and it can alleviate the growing shortage of non-renewable fossil fuels at the same time.

The electrochemical reduction of CO₂ to value-added products obtains great attention and investigation worldwide in recent years owing to its mild reaction conditions and high energy efficiency. However, it remains a challenge to maintain a high current efficiency in a wide negative potential range for achieving a high production rate of the target products.

Recently, a research team led by Prof. LIU Licheng from Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT), Chinese Academy of Sciences (CAS), achieved efficient electrocatalytic conversion of CO₂ to formate over a wide negative potential range successfully.

The researchers developed a new composite catalyst composed of bismuth oxide nanosheets and nitrogen-doped graphene quantum dots (Bi₂O₃-NGQDs), demonstrating an average current efficiency of 95.6% over a wide negative potential range from -0.9 V to -1.2 V vs. reversible hydrogen electrode. They found that the origin of high activity is the significant synergistic effect among Bi₂O₃ and NGQDs in increasing adsorption energy of adsorbed CO₂ and OCHO* intermediate.

Furthermore, this study reveals that NGQDs can not only enhance the activity of Bi₂O₃, but can also enhance the activity of other metal oxides such as SnO₂. This work opens up a facile avenue for enhancing activity of some metal oxides in a wide negative potential range.

The related progresses were published in Angewandte Chemie . This work was supported by the National Natural Science Foundation of China.

Figure. Schematic illustration of the fabrication process for Bi₂O₃-NGQDs and the CO₂ electrocatalytic reduction process. (Image by CHEN Zhipeng)

(Text by CHEN Zhipeng)

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