Electroenzymatic CO₂ Reduction Through Hollow Covalent Organic Framework-Immobilized Enzyme With Neutral Red-Modified...

Area of Science:

• Electrochemistry
• Biocatalysis
• Materials Science

Background:

• Carbon neutrality goals drive interest in CO2 conversion technologies.
• Electroenzymatic CO2 reduction faces challenges like low CO2 solubility, enzyme instability, and cofactor costs.
• Need for efficient systems to overcome limitations in CO2 capture and conversion.

Purpose of the Study:

• To develop a novel system for enhanced electroenzymatic CO2 reduction.
• To improve CO2 solubility and enzyme stability using a covalent organic framework (COF).
• To establish an efficient electrochemical NADH regeneration coupled with enzyme catalysis.

Main Methods:

• Synthesis of a spherical covalent organic framework (COF), TPB-DMTP, for CO2 enrichment and enzyme immobilization.
• Covalent attachment of neutral red as an electron mediator to a carbon paper electrode for electrochemical NADH regeneration.
• Immobilization of formate dehydrogenase (FDH) within the COF matrix and coupling with the electrochemical system.

Main Results:

• The TPB-DMTP COF effectively enriched CO2 near immobilized enzyme molecules.
• Enzyme stability and reusability were significantly enhanced after immobilization in the COF.
• The optimized system achieved a formate production of 2.312 mM, a 4.01-fold increase compared to free enzyme systems.

Conclusions:

• The developed COF-based electrocatalytic system offers a promising strategy for efficient CO2 conversion.
• Enzyme immobilization in COFs improves stability and performance in electroenzymatic reactions.
• Electrochemical NADH regeneration provides a cost-effective and stable alternative to traditional cofactor systems.