Semi-Ionic C-F Bonds Modulate Hydrogen Dynamics for Selective CO₂-to-CH₄ Electroreduction on Carbon Quantum Dots

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical CO2 reduction to CH4 is key for carbon recycling and energy storage.
• Current methods face challenges with slow hydrogenation and poor hydrogen management.

Purpose of the Study:

• Develop a novel catalyst for efficient electrochemical CO2 reduction to CH4.
• Investigate the structure-activity relationship of fluorine-rich carbon quantum dots.

Main Methods:

• Synthesized fluorine-rich carbon quantum dots (F1-CQDs) using a molecular fusion strategy.
• Characterized F1-CQDs for fluorine content and catalytic performance in a flow cell.
• Employed in situ spectroscopy, theoretical calculations, isotope labeling, and H-scavenging experiments.

Main Results:

• Achieved unprecedented F content up to 28.8 at. % in F1-CQDs.
• Catalyst demonstrated 63.2% CH4 Faraday efficiency and 210.8 mA cm-2 CH4 partial current density.
• Identified semi-ionic C-F bonds as Lewis basic sites stabilizing CO2 intermediates and regulating hydrogen dynamics.

Conclusions:

• F1-CQDs offer synergistic dual-site functionality for enhanced CO2 reduction.
• Established a structure-activity relationship between C-F bonding and catalytic performance.
• Provided a design principle for metal-free electrocatalysts via intermediate stabilization and hydrogen kinetics engineering.