Nitrogen‐Doped Graphene Quantum Dots Enhance the Activity of Bi₂O₃ Nanosheets for Electrochemical Reduction of CO₂ in a Wide Negative Potential Region

Abstract

Large numbers of catalysts have been developed for the electrochemical reduction of CO 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 (Bi O -NGQDs) for highly efficient electrochemical reduction of CO to formate. Bi O -NGQDs demonstrates a nearly 100 % formate Faraday efficiency (FE) at a moderate overpotential of 0.7 V with a good stability. Strikingly, Bi O -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 CO (ads) and OCHO* intermediate after combination with NGQDs.

Morphology Modulation‐Engineered Flowerlike In2S3 via Ionothermal Method for Efficient CO2 Electroreduction

“…The value is close to the slope of 120 mV dec −1 , which means the rate‐determining step is an initial electron transfers to adsorbed CO 2 molecule forming CO 2 − anionic radical . The electrochemically active surface area (ECSA) has significant effect on electroreduction of CO 2 . Therefore, the ECSA of flowerlike In 2 S 3 and bulk In 2 S 3 were estimated from their electrochemical double‐layer capacitance (C dl ) (Figure c), which was obtained from the CVs at different scan rates (Figure S12).…”

Boosting Electrochemical Reduction of CO2 at a Low Overpotential by Amorphous Ag‐Bi‐S‐O Decorated Bi0 Nanocrystals

“…[7,18] To verify the local pH effect, we examined the formate FE of AgBi-500 and Bi-500 in three electrolytes with different buffer capacity at ac onstant current density.F igure 3e illustrates that with the local pH increasing,t he formate FE of AgBi-500 and Bi-500 both increased, which confirms that ahigh local pH was preferred for eCO 2 RR than H 2 evolution. [19] In summary,wehave developed an amorphous Ag-Bi-S-O decorated Bi 0 nanocatalyst derived from Ag 0.95 BiS 0.75 O 3.1 nanorods,w hich exhibited af ormate FE of 94.3 %w ith af ormate partial current density of 12.52 mA cm À2 at al ow overpotential. Now,w ec ould conclude that at more positive potentials,t he existence of Ag in AgBi-500 would greatly enhance the geometric current density,r esulting in ah igher local pH and thus Ss pecies on the surface would accelerate the dissociation of H 2 Om ore dramatically.B esides,H 2 evolution would be suppressed more significantly.T hat is why AgBi-500 exhibited as uperior formate FE at al ow overpotential.…”

Two‐Dimensional Electrocatalysts for Efficient Reduction of Carbon Dioxide

“…Chen et al. reported the synthesis of a nanocomposite catalyst that consisted of bismuth oxide NSs and nitrogen‐doped graphene quantum dots (Bi 2 O 3 ‐NGQDs; Figure a), through a solvothermal method in polyol media . This composite catalyst produces a larger current density and a more positive onset potential than Bi 2 O 3 or NGQDs (Figure b).…”

“…e) Calculated adsorption energies of CO 2 , OCHO*, and HCOOH(ads). Reproduced with permission . Copyright 2018, Wiley‐VCH.…”