Nitrogen-Doped Graphene Quantum Dots Enhance the Activity of Bi2 O3 Nanosheets for Electrochemical Reduction of CO2 in a Wide Negative Potential Region.

Large numbers of catalysts have been developed for the electrochemical reduction of CO2 to value-added liquid fuels. 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. Herein, we report a 2D/0D composite catalyst composed of bismuth oxide nanosheets and nitrogen-doped graphene quantum dots (Bi2 O3 -NGQDs) for highly efficient electrochemical reduction of CO2 to formate. Bi2 O3 -NGQDs demonstrates a nearly 100 % formate Faraday efficiency (FE) at a moderate overpotential of 0.7 V with a good stability. Strikingly, Bi2 O3 -NGQDs exhibit a high activity (average formate FE of 95.6 %) from -0.9 V to -1.2 V vs. RHE. Additionally, DFT calculations reveal that the origin of enhanced activity in this wide negative potential range can be attributed to the increased adsorption energy of CO2 (ads) and OCHO* intermediate after combination with NGQDs.