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

Abstract

Abstract Microenvironment regulation of M‐N 4 single‐atom catalysts (SACs) is a promising way to tune their catalytic properties toward the electrochemical CO 2 reduction reaction. However, strategies that can effectively introduce functional groups around the M‐N 4 sites through strong covalent bonding and under mild reaction conditions are highly desired. Taking the hydrophilic Ni‐N 4 SAC as a representative, we report herein a [2+1] cycloaddition reaction between Ni‐N 4 and in situ generated difluorocarbene (F 2 C:), and enable the surface fluorocarbonation of Ni‐N 4 , resulting in the formation of a super‐hydrophobic Ni‐N 4 ‐CF 2 catalyst. Meanwhile, the mild reaction conditions allow Ni‐N 4 ‐CF 2 to inherit both the electronic and structural configuration of the Ni‐N 4 sites from Ni‐N 4 . Enhanced electrochemical CO 2 ‐to‐CO Faradaic efficiency above 98 % is achieved in a wide operating potential window from −0.7 V to −1.3 V over Ni‐N 4 ‐CF 2 . In situ spectroelectrochemical studies reveal that a highly hydrophobic microenvironment formed by the −CF 2 − group repels asymmetric H‐bonded water at the electrified interface, inhibiting the hydrogen evolution reaction and promoting CO production. This work highlights the advantages of [2+1] cycloaddition reactions on the covalent modification of N‐doped carbon‐supported catalysts.