Nanoconfinement promotes CO₂ electroreduction to methanol on a molecular catalyst

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Nanoconfinement strategies can regulate catalytic processes by controlling intermediate configurations and product distributions.
• Electrochemical conversion of carbon dioxide (CO2) to valuable products like methanol (CH3OH) is a key area in sustainable chemistry.
• Molecular catalysts offer tunability but often face challenges in selectivity and stability.

Purpose of the Study:

• To investigate the use of carbon nanotubes (CNTs) as nanoreactors for the electrochemical conversion of CO2 to CH3OH.
• To explore the effect of confining cobalt phthalocyanine (CoPc) molecules within CNTs on CH3OH selectivity.
• To elucidate the mechanisms behind enhanced CH3OH production via nanoconfinement.

Main Methods:

• Synthesis of CoPc-incorporated CNTs with varying diameters.
• Electrochemical measurements, including CO2 reduction reactions.
• Operando spectroelectrochemical analysis.
• Density Functional Theory (DFT) calculations.

Main Results:

• CoPc confined within CNTs significantly enhances CH3OH selectivity compared to exterior CoPc.
• Nanoconfinement promotes CO accumulation as a key intermediate for CH3OH production.
• Structural deformation of CoPc and enhanced CO adsorption on Cobalt sites were observed within CNTs.
• CNT diameter influences the CH3OH selectivity, indicating the importance of the nanospace dimensions.

Conclusions:

• The inner cavity of CNTs serves as an effective nanoreactor for CO2 electroreduction to CH3OH.
• Nanoconfinement of molecular catalysts like CoPc is a viable strategy to improve selectivity for deep-reduction products.
• Understanding the interplay between the catalyst and its nanoconfined environment is crucial for designing efficient electrocatalysts.