Conjugation of metal-organic framework (MIL-125) to NiFe2O4@CdS nanoparticles for enhanced photocatalytic hydrogen generation

Abstract Harnessing solar energy with semiconductors offers a feasible path toward sustainable hydrogen production via photocatalytic water splitting. In this study, a ternary photocatalyst, MIL-125(Ti)/NiFe 2 O 4 @CdS, was fabricated by integrating a Ti-based metal–organic framework with a green-synthesized NiFe 2 O 4 @CdS binary core–shell heterostructure for visible-light-driven hydrogen evolution. Illicium verum Hook. f. (star anise) extract was used as a natural reducing and stabilizing agent for NiFe 2 O 4 nanoparticles preparation prior to the fabrication of the binary photocatalyst. The ternary composite was comprehensively characterized by structural, morphological, optical, and photoelectrochemical techniques. Compared with the individual components, the ternary photocatalyst exhibited enhanced visible-light absorption, a reduced band gap (2.42 eV), and a mesoporous structure with a BET surface area of 148.62 m²/g, pore volume of 0.5721 cm 3 /g, and a mean pore diameter of 15.0 nm. Photoelectrochemical analyses revealed improved charge separation, the lowest charge-transfer resistance, the highest photocurrent response, the largest electrochemically active surface area, and favorable band alignment. Consequently, MIL-125/NiFe 2 O 4 @CdS achieved an initial hydrogen evolution rate of 1.62231 mmol g − 1 h − 1 and a cumulative hydrogen production of 10.20386 mmol g − 1 after 5 h, significantly outperforming CdS and the binary NiFe 2 O 4 @CdS. The photocatalyst retained approximately 60% of its initial activity after four reaction cycles, demonstrating good stability. The enhanced performance is attributed to the synergistic effects of MIL-125, which increase surface area, improve light harvesting, and promote efficient charge separation and transfer through a dual direct Z-scheme heterojunction. These findings highlight MIL-125/NiFe 2 O 4 @CdS as a promising photocatalyst for sustainable hydrogen production.