Local CO₂ reservoir layer promotes rapid and selective electrochemical CO₂ reduction

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Electrochemical CO2 reduction is key for sustainable chemical production.
• Low CO2 solubility in aqueous electrolytes limits reaction efficiency in Gas-Diffusion Electrode devices.

Purpose of the Study:

• To develop a CO2-solvation layer using a nitrile-modified Metal-Organic Framework (MOF).
• To enhance the rate and selectivity of electrochemical CO2 reduction to formic acid (HCOOH).

Main Methods:

• Assembling a nitrile-modified MOF film over a heterogeneous electrocatalyst.
• Utilizing a Gas Diffusion Electrode setup with a Bismuth (Bi) catalyst.
• Employing operando infrared spectroscopy and Density Functional Theory (DFT) for mechanistic studies.

Main Results:

• The MOF film increased local CO2 concentration by ~27-fold (0.82 M).
• Achieved >90% selectivity for CO2 to HCOOH conversion.
• Reached partial HCOOH currents of 166 mA/cm2 at -0.9 V vs RHE.
• MOF facilitated catalysis via stabilization of reaction intermediates.

Conclusions:

• Nitrile-modified MOF films act as effective CO2-solvation layers.
• This strategy significantly enhances electrochemical CO2 reduction performance.
• The approach offers a molecular solution for practical implementation of CO2 conversion technologies.