Metalloporphyrin-Sensitized Ti Metal–Organic Framework Nanostructures for Visible-Light-Driven Hydrogen Evolution

Abstract

Effective combination of the photosensitive and photoactive units in metal–organic frameworks (MOFs) is vital to achieving efficient solar energy utilization for superior photocatalytic efficiency. In this study, we successfully organize photosensitive metalloporphyrin ligands and photoactive building units (Ti-oxo clusters) uniformly at a molecular level within a heterobimetallic metal–organic framework (MOF) nanostructure, denoted as TMF(X), where X represents Zn, Co, or Cu. The well-accessible Ti sites possess a close proximity to the metalized porphyrin, which is favorable for the electron-transfer kinetics to the photocatalytic center for the redox reaction. Furthermore, the metal ions at the porphyrin center are able to induce electron redistribution, more negative conduction band potential, and enhanced light absorption, which boosts the photocatalytic H₂ evolution performance. Notably, the resulting heterobimetallic MOF nanostructures exhibited remarkably enhanced photocatalytic H₂ evolution performance, especially for the nano TMF(Zn) with a maximum H₂ evolution rate of 3.24 mmol g^–1 h^–1 under visible light irradiation, which is much higher than that of TMF (1.40 mmol g^–1 h^–1). Our work opens up a way for highly efficient MOF-based photocatalysts for H₂ evolution and beyond.