Adsorption-Enhanced Bismuth Oxide Efficiently Convert CO₂ to Formate Over a Wide Potential Window

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical conversion of carbon dioxide (CO2) is crucial for reducing emissions and storing energy.
• Limited CO2 adsorption and activation hinder efficient electrochemical reduction.
• Developing advanced catalysts is essential for enhancing CO2 electroreduction performance.

Purpose of the Study:

• To synthesize CO2 adsorption-enhanced bismuth oxide nanosheets (syn-Bi2O3) for improved electrochemical CO2 reduction.
• To investigate the catalytic performance of syn-Bi2O3 for formate production.
• To evaluate the solar-driven formate production efficiency using syn-Bi2O3.

Main Methods:

• One-pot low-temperature water bath synthesis of bismuth oxide nanosheets.
• Electrochemical characterization in a flow cell, including Faradaic efficiency and partial current density measurements.
• In situ spectroscopy and theoretical calculations to elucidate reaction mechanisms.
• Coupling with simulated solar cells for solar-to-fuel efficiency assessment.

Main Results:

• Syn-Bi2O3 demonstrated high Faradaic efficiency (FEformate) over 94% in a wide potential window (-0.43 to -1.31 V vs RHE).
• Achieved an FEformate of 94.5% at a partial current density of 661.9 mA cm-2.
• Solar-to-formate and overall solar-to-fuel efficiencies reached 19.34% and 20.23%, respectively, with significant current output.
• In situ spectroscopy and calculations confirmed CO2 adsorption and intermediate promotion by syn-Bi2O3.

Conclusions:

• Syn-Bi2O3 is an effective catalyst for electrochemical CO2 reduction to formate.
• The catalyst's performance is attributed to enhanced CO2 adsorption and activation.
• This work demonstrates the potential of solar-driven electrochemical CO2 reduction for sustainable formate production.