Space-Confined Molecular\nCatalysis toward Electrocatalytic\nCO<sub>2</sub> Reduction on Metal Phthalocyanine@Nitrogen-Doped Carbon\nNanosheet

Phthalocyanines have emerged as attractive materials\nfor electrocatalytic\ncarbon dioxide reduction. However, the challenge of finding a support\nthat is stable while maintaining catalytic activity and loading remains\nelusive. Porous carbon materials are considered reliable substrates\nfor supporting molecular catalysts. Herein, a nitrogen-rich carbon\nnanosheet (NiPc/NMCN) with multilayer and mesoporous structure is\nsynthesized based on a kinetically controlled self-assembly strategy\nand used for phthalocyanine loading. The multilayer composite structure\nof NMCN guides the molecular-scale dispersion of phthalocyanine and\nplays a crucial role in its catalytic process. Moreover, the phthalocyanine\nmolecules retain their metal-N<sub>4</sub> structure after impregnation.\nTherefore, the remarkable CO<sub>2</sub> electroreduction properties\nof phthalocyanine are fully demonstrated. At −0.73 V vs. RHE,\nNiPc/NMCN achieves the highest CO faradaic efficiency (FE<sub>CO</sub>) of 96.0%. Meanwhile, current densities in membrane electrode module\nelectrolyzers can reach industrial amperage levels, while the FEco\nremains at 60% at 880 mA cm<sup>–2</sup>. Density functional\ntheory (DFT) indicates that the high performance of NiPc/NMCN is attributed\nto the significant reduction of the CO<sub>2</sub>RR energy barrier.\nPhthalocyanines restricted by the porous carbon could produce the\nintermediate *COOH more rapidly, determining high CO<sub>2</sub>RR\nselectivity, which is confirmed by in situ (FTIR) spectroscopy. Consequently,\nthe strategy of constructing confined multilayer mesoporous carbon\nstructures provides an avenue for the design of efficient CO<sub>2</sub> reduction molecular catalysts.