Self-assembly of iron porphyrin complexes bearing carboxyl and carboxylate groups for a highly active CO₂ reduction...

Developing efficient catalysts for CO₂ reduction is a promising approach to address energy and environmental challenges. Molecule-based heterogeneous catalysts are attractive because they combine the advantages of homogeneous and heterogeneous catalysts. Achieving an efficient CO₂ reduction catalyst requires the integration of the functions that facilitate the following three key processes; (i) chemical conversion, (ii) substrate accumulation, and (iii) proton transport. However, such function-integrated systems for CO₂ reduction have not been reported thus far. In this study, we integrated a porous structure and a hydrogen-bonding network via the self-assembly of a molecular catalyst containing an iron porphyrin complex, which is a well-known catalytic center for CO₂ reduction. The resulting material exhibited the highest CO₂ reduction activity under photochemical conditions (1.8 × 10⁶ µmol g^-1 h^-1 for CO production, selectivity > 99%) among the related systems owing to its function-integrated crystalline structure. This study provides a versatile strategy for designing highly active molecule-based heterogeneous catalysts for efficient CO₂ reduction.