Space-Confined Molecular Catalysis toward Electrocatalytic CO₂ Reduction on Metal Phthalocyanine@Nitrogen-Doped Carbon Nanosheet

Phthalocyanines have emerged as attractive materials for electrocatalytic carbon dioxide reduction. However, the challenge of finding a support that is stable while maintaining catalytic activity and loading remains elusive. Porous carbon materials are considered reliable substrates for supporting molecular catalysts. Herein, a nitrogen-rich carbon nanosheet (NiPc/NMCN) with multilayer and mesoporous structure is synthesized based on a kinetically controlled self-assembly strategy and used for phthalocyanine loading. The multilayer composite structure of NMCN guides the molecular-scale dispersion of phthalocyanine and plays a crucial role in its catalytic process. Moreover, the phthalocyanine molecules retain their metal-N4 structure after impregnation. Therefore, the remarkable CO2 electroreduction properties of phthalocyanine are fully demonstrated. At −0.73 V vs. RHE, NiPc/NMCN achieves the highest CO faradaic efficiency (FECO) of 96.0%. Meanwhile, current densities in membrane electrode module electrolyzers can reach industrial amperage levels, while the FEco remains at 60% at 880 mA cm–2. Density functional theory (DFT) indicates that the high performance of NiPc/NMCN is attributed to the significant reduction of the CO2RR energy barrier. Phthalocyanines restricted by the porous carbon could produce the intermediate *COOH more rapidly, determining high CO2RR selectivity, which is confirmed by in situ (FTIR) spectroscopy. Consequently, the strategy of constructing confined multilayer mesoporous carbon structures provides an avenue for the design of efficient CO2 reduction molecular catalysts.