[2+1] Cycloadditions Modulate the Hydrophobicity of Ni-N₄ Single-Atom Catalysts for Efficient CO₂ Electroreduction

Area of Science:

• Catalysis
• Materials Science
• Electrochemistry

Background:

• Microenvironment engineering of M-N4 single-atom catalysts (SACs) is key for optimizing electrochemical CO2 reduction.
• Mild, covalent functionalization strategies for M-N4 sites are needed.

Purpose of the Study:

• To develop a mild method for surface functionalization of Ni-N4 SACs.
• To investigate the impact of fluorocarbonation on catalytic performance for CO2 reduction.

Main Methods:

• A [2+1] cycloaddition reaction between Ni-N4 SACs and in situ generated difluorocarbene.
• Surface fluorocarbonation to form Ni-N4-CF2 catalysts.
• In situ spectroelectrochemical studies.

Main Results:

• Formation of a super-hydrophobic Ni-N4-CF2 catalyst preserving Ni-N4 site integrity.
• Achieved >98% Faradaic efficiency for CO2-to-CO conversion over a wide potential window (-0.7 to -1.3 V).
• Hydrophobic -CF2 groups were shown to repel water, suppressing hydrogen evolution and promoting CO production.

Conclusions:

• [2+1] cycloaddition enables effective covalent modification of N-doped carbon catalysts.
• Surface fluorocarbonation creates a favorable microenvironment for selective CO2 reduction.
• This strategy offers a new pathway for designing advanced SACs.