Graphene Framework Pillared by Co-Metalated Porphyrin Linker as CO2 Reduction Electrocatalyst.

Abstract

Developing low-cost, efficient, and durable electrocatalysts for CO2 conversion remains a significant challenge. Herein, we report a Co-metalated porphyrinic pillared graphene framework (Co-P-PGF) that functions as a single-atom catalyst (SAC) for efficient electrochemical CO2 reduction. The framework was synthesized via Sonogashira-Hagihara coupling between Co-porphyrin linkers and iodobenzene-functionalized reduced graphene oxide (rGO), alongside a metal-free analogue (P-PGF). The atomically dispersed Co(II) centers serve as active sites for CO2 binding and activation, while the conductive rGO sheets facilitate rapid electron transport and efficient charge transfer at the electrode-electrolyte interface. Owing to the integrated conductive graphene architecture, Co-P-PGF exhibits excellent intrinsic electrocatalytic activity without requiring additional conductive carbon additives. The catalyst achieves a remarkable Faradaic efficiency for CO production (FECO = 94.07%) in aqueous electrolyte in an H-cell configuration. Furthermore, operation in a flow cell results in a six-fold enhancement in current density compared to the H-cell. Operando DRIFTS, Raman spectroscopy, and X-ray absorption spectroscopy, complemented by density functional theory calculations, reveal the nature of the active sites and reaction intermediates during CO2 reduction. These results highlight the promise of graphene-based SACs as cost-effective, sustainable, and high-performance catalysts for electrochemical CO2 reduction reaction (CO2RR).