Three-ligand Ti-MOFs for high-efficient photocatalytic H2 evolution

The design and construction of high-performance photocatalysts with both strong visible light harvesting and effective electron transfer are highly desired in the photocatalysis field. Herein, a multi-ligand strategy based on the MOF materials is proposed. A three-ligand Ti-MOF EY/NH2/H-MIL-125 (ENHM) was prepared via a facile hydrothermal method, in which 2-aminoterephthalic acid (NH2-H2BDC), terephthalic acid (H2BDC) and Eosin Y (EY) were employed as three ligands. The push–pull effect induced by different substituent groups (–NH2 and –H) on the skeleton of NH2-H2BDC and H2BDC promotes the efficient transfer of photogenerated electrons from organic ligands to metal nodes; while the third ligand EY increases the number of photoexcited electrons by enhancing the visible light absorption ability. Among the three-ligand MOF photocatalytic materials, ENHM-2 performs the optimal H2 production activity of 2.15 mmol g−1 h−1, much higher than dual-ligand NH2/H-MIL-125 and EY/NH2-MIL-125 and single-ligand NH2-MIL-125. A probable mechanism was also proposed for the three-ligand MOFs. This multi-ligand strategy may open up a new direction toward the preparation of MOF-based photocatalytic materials with excellent photocatalytic performances.