Spatially-Directed C─C Coupling inside Three-dimensional Metal-organic Frameworks for CO₂ Electroreduction to C₂...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Carbon dioxide (CO2) electroreduction is key for renewable energy storage and carbon cycle management.
• Producing multi-carbon products (C2+) from CO2 is desirable but challenging due to difficult C-C coupling.
• Existing methods often suffer from high energy input, low rates, and poor selectivity.

Purpose of the Study:

• To design and synthesize a novel electrocatalyst for efficient CO2 electroreduction to C2 products.
• To investigate the mechanism of C-C coupling facilitated by dual Fe sites in a metal-organic framework.
• To achieve high activity and selectivity for C2 oxygenates and hydrocarbons.

Main Methods:

• Construction of a 3D Fe-quinoxalinedithiol (Fe-QDT) metal-organic framework (MOF).
• Characterization of the MOF's structure and dual Fe active sites.
• Electrochemical evaluation of CO2 reduction performance, including activity, selectivity, and energy efficiency.

Main Results:

• The Fe-QDT MOF features dual Fe sites within ordered channel walls for interwall electrocatalysis.
• Dual Fe sites effectively co-catalyze the dimerization of *OCH2 intermediates, promoting C2 product formation.
• Achieved significantly low free energy changes for potential-limiting steps in C2 species electroreduction (-0.010 eV for ethanol, 0.045 eV for ethylene).

Conclusions:

• The Fe-QDT MOF demonstrates high activity and selectivity for converting CO2 to ethanol and ethylene.
• This work presents an efficient active site design for C-C coupling in CO2 electroreduction.
• Provides insights into designing electrocatalysts for valuable C2 products from CO2.