Porphyrin-Based Metal-Organic Frameworks for Efficient Photocatalytic H₂ Production under Visible-Light Irradiation

Metal-organic frameworks (MOFs) are important photocatalytic materials for H₂ production. To clarify the structure-function relationship and improve the photocatalytic activity, herein we explored a series of porphyrin-based zirconium MOFs (PCN-H₂/Pt, where x:y = 4:1, 3:2, 2:3, and 0:1) containing different ratios of H₂TCPP and Pt^IITCPP [TCPP = tetrakis(4-carboxyphenyl)porphyrinate] as isostructural ligands and Zr₆ clusters as nodes. Under visible-light irradiation, PCN-H₂/Pt_0:1 shows the highest average H₂ evolution reaction rate (351.08 μmol h^-1 g^-1), which decreases along with lowering of the ratio of Pt^IITCPP in the PCN-H₂/Pt series. The differences in photocatalytic activity are attributed to more uniformly dispersed Pt²⁺ ions in PCN-H₂/Pt_0:1, which promotes charge transfer from porphyrins (photosensitizers) to Pt^II ions (catalytic centers), leading to efficient charge separation in the MOF materials. The bifunctional MOFs with photosensitizers and catalytic centers provide new insight for the design and application of porphyrin-based photocatalytic systems for visible-light-driven H₂ production.