Bismuth oxide-loaded indium-organic framework catalysts for efficient electrochemical CO₂ reduction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrocatalytic CO2 reduction is crucial for sustainable chemical production.
• Metal-organic frameworks (MOFs) offer tunable structures for catalysis.
• Improving selectivity and efficiency in CO2 reduction remains a challenge.

Purpose of the Study:

• To investigate the use of bismuth oxide-loaded indium-organic framework (MIL-68(In)) catalysts for electrocatalytic CO2 reduction.
• To enhance formic acid production efficiency and selectivity.
• To understand the role of bismuth incorporation in catalytic performance.

Main Methods:

• Synthesis of bismuth-modified MIL-68(In) catalysts.
• Electrocatalytic CO2 reduction experiments in an H-type cell.
• Faradaic efficiency measurements.
• Characterization of catalyst properties (e.g., conductivity, active sites).
• Theoretical calculations (e.g., DFT) to study reaction mechanisms.

Main Results:

• The Bi1/2@MIL-68(In) catalyst achieved a high Faradaic efficiency of 96.9% for formic acid production at -1.7 V (vs. Ag/AgCl).
• Bismuth incorporation increased reactive sites, reduced energy barriers, and enhanced conductivity and electron transfer.
• CO2 adsorption and activation were facilitated by the integration of Bi2O3 into the MOF framework.
• Theoretical calculations confirmed stabilization of the HCOO* intermediate, lowering the free energy barrier for formic acid formation.

Conclusions:

• Bismuth oxide-loaded MIL-68(In) is a highly effective catalyst for selective CO2 reduction to formic acid.
• MOFs serve as excellent platforms for incorporating secondary metals to boost catalytic activity.
• The findings offer valuable insights for designing advanced electrocatalysts for CO2 utilization.