Photocatalytic CO₂ Reduction to Solar Fuels by a Chemically Stable Bimetallic Porphyrin-Based Framework

Porphyrin-based photocatalysts have emerged as promising candidates for facilitating carbon dioxide (CO₂) reduction due to their exceptional light-harvesting properties. However, their performance is hindered by complex synthesis procedures, limited structural stability, inadequate CO₂ activation capabilities, and a lack of comprehensive structure-property relationships. This study investigates the performance of a porphyrin-based bimetallic framework, [Cu(TPP)Cu₂Mo₃O₁₁] (TPP = tetrapyridylporphyrin), termed MoCu-1 for photocatalytic CO₂ reduction. In addition to its straightforward one-pot synthesis method, the framework shows remarkable chemical stability, particularly notable in alkaline reaction conditions, making it a compelling option for sustainable catalytic applications. By harnessing the superior photoabsorption properties of the porphyrin linker and the abundance of catalytic sites provided by the bimetallic structure, this framework exhibits the potential for enhancing CO₂ reduction efficiency. MoCu-1 demonstrates excellent activity in converting CO₂ into CO, achieving a maximum yield of 3.21 mmol g^-1 with a selectivity of ∼93%. We unravel the intricate interplay of structural features and catalytic activity through systematic characterization techniques and an in situ diffuse reflectance Fourier transform study, which provided insights into the mechanism governing CO₂ conversion and was supported by density functional theory calculations. This work contributes to advancing our understanding of photocatalytic processes and offers guidance for designing robust materials for CO₂ utilization in renewable energy applications.