Breaking π Electron Network in Carbon Planes Enables Electron‐Localized NiN ₄ Moieties for Efficient Electrochemical CO ₂ Reduction

ABSTRACT Graphene‐based metal‐nitrogen‐carbon single atom catalysts (M−NC SACs) have been used extensively for electrochemical CO 2 reduction reaction (eCO 2 RR). Yet, CO 2 adsorption and activation on the metal sites are hindered by the intense electron confinement in the carbon scaffold. This issue can be mitigated by breaking the π electron network of the carbon planes, forming electron‐localized MN x sites that enhances the eCO 2 RR performance. Herein, Ni−NC SACs are prepared pyrolytically on carbon scaffolds derived from thermal reconstruction of fullerene, where NiN 4 moieties are embedded within an asymmetrical carbon matrix featuring a mix of pentagonal and hexagonal carbon rings. Among the series, the sample prepared at 900°C (Ni 1 −NC as −900) stands out with a maximum CO partial current density of −280.6 mA cm −2 , maximum CO Faraday efficiency of 97.13%, and stable eCO 2 RR operation at −150 mA cm −2 for 20 h. Such a performance is 11.4 times greater than that with symmetrical graphene nanosheets (Ni 1 −NC sy −900). This is due to electron enrichment of the NiN 4 moieties in Ni 1 −NC as −900 that facilitates adsorption and activation of CO 2 and stabilization of the * COOH intermediate, as confirmed in theoretical studies and in situ spectroscopy measurements, highlighting the significance of carbon substrate engineering in enhancing eCO 2 RR performance of M−NC SACs.