Cage-Confined Cu Clusters Boost Carbon Dioxide Electroreduction into Methane.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Microgeometric structures of copper (Cu) are crucial for selective carbon dioxide (CO2) electroreduction.
• Metal-organic frameworks (MOFs) offer tunable environments for catalytic applications.

Purpose of the Study:

• To fabricate sub-nanometer Cu clusters confined in UIO-66-NDC for efficient methane (CH4) synthesis via CO2 electroreduction.
• To elucidate the mechanism of CH4 formation and identify key intermediates.

Main Methods:

• Fabrication of Cu clusters confined within UIO-66-NDC.
• Electrochemical characterization of CO2 electroreduction.
• In situ characterization techniques (spectroscopy, etc.).
• Theoretical calculations (DFT).

Main Results:

• Cu clusters confined in UIO-66-NDC achieved 72.0% faradaic efficiency for CH4 and -361.0 mA cm-2 partial current density.
• In situ studies revealed the formation of Cu clusters with coordination number ~7 in octahedral cages.
• In situ spectroscopy indicated favorable adsorption of bridged CO (*CO_bridge) on Cu cluster surfaces.

Conclusions:

• The UIO-66-NDC framework effectively confines Cu clusters, enhancing CH4 selectivity during CO2 electroreduction.
• The mechanism favors *CO_bridge protonation over C-C coupling, leading to high CH4 yields.
• This work presents a promising strategy for designing efficient electrocatalysts for CO2 conversion.