Stabilizing Reticular Frameworks and Modulating Interfacial Water via Conductive Polymer Encapsulation in...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical reduction of carbon dioxide (CO2) to methane (CH4) is a key technology for renewable energy storage.
• Challenges include slow reaction kinetics, catalyst degradation, and competing hydrogen evolution reactions (HER).

Purpose of the Study:

• To develop novel metal-organic framework (MOF) electrocatalysts for efficient CO2-to-CH4 conversion.
• To investigate the role of conductive polymer encapsulation in enhancing catalyst performance and stability.

Main Methods:

• A host-guest strategy was employed, encapsulating conductive polymers (polypyrrole and polyaniline) within Cu-anchored UiO-67 MOFs.
• Characterization included X-ray diffraction (XRD), Raman spectroscopy, and attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS).
• Electrochemical performance was evaluated by measuring CH4 Faradaic efficiency (FECH4) and suppressing HER.

Main Results:

• Hybrid catalysts, PPy@Cu-UiO-67 and PANI@Cu-UiO-67, were successfully synthesized with preserved MOF crystallinity and enhanced conductivity.
• PANI@Cu-UiO-67 demonstrated superior performance, achieving a CH4 Faradaic efficiency of up to 71.1%.
• Spectroscopic analyses indicated that the conductive polymers stabilized the MOF structure and modulated the interfacial water network, favoring weakly hydrogen-bonded water (2-HB·H2O).

Conclusions:

• Encapsulating conductive polymers within MOFs is an effective strategy to enhance CO2 electroreduction to CH4.
• The PANI@Cu-UiO-67 catalyst promotes efficient proton transfer and suppresses HER, leading to high CH4 selectivity.
• This approach offers a promising route for designing advanced electrocatalysts for sustainable energy applications.