Porphyrin-based Bi-MOFs with Enriched Surface Bi Active Sites for Boosting Photocatalytic CO₂ Reduction

The inherent challenges in using metal-organic frameworks (MOFs) for photocatalytic CO₂ reduction are the combination of wide-range light harvesting, efficient charge separation and transfer as well as highly exposed catalytic active sites for CO₂ activation and reduction. We present here a promising solution to satisfy these requirements together by modulating the crystal facet and surface atomic structure of a porphyrin-based bismuth-MOF (Bi-PMOF). The series of structural and photo-electronic characterizations together with photocatalytic CO₂ reduction experiment collectively establish that the enriched Bi active sites on the (010) surface prefer to promote efficient charge separation and transfer as well as the activation and reduction of CO₂ . Specifically, the Bi-PMOFs-120-F with enriched surface Bi active sites exhibits optimal photocatalytic CO₂ reduction performance to CO (28.61 μmol h^-1 g^-1 ) and CH₄ (8.81 μmol h^-1 g^-1 ). This work provides new insights to synthesize highly efficient main group p-block metal Bi-MOF photocatalysts for CO₂ reduction through a facet-regulation strategy and sheds light on the surface structure-activity relationships of the MOFs.