An iron-porphyrin grafted metal–organic framework as a heterogeneous catalyst for the photochemical reduction of CO2

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Photocatalytic reduction of carbon dioxide (CO 2 ) into value-added carbon products is a promising strategy for dealing with carbon emission. Selected metal–organic frameworks (MOFs) have been shown promise in photocatalytic CO 2 reduction owing to their photochemical activity and structural modularity. Here, we take advantage of displaceable nonstructural ligands on the nodes of a pyrene-based MOF, NU-1000, to graft a molecular catalyst, tetra(4-carboxyphenyl) porphyrin iron (III) chloride (Fe-TCPP). The pyrene linkers in the MOF absorb photons and transfer electrons to the porphyrin catalyst, resulting in a self-contained photocatalyst. The obtained Fe-TCPP@NU-1000 heterogeneous catalysts exhibit activity for CO 2 photoreduction under illumination at 390 nm, with a TON for CO of 22 in 2 h. Molecular hydrogen is co-evolved. Leaching of the grafted catalyst from the MOF ultimately limits performance.