Boosting solar hydrogen generation by growth of UiO-based MOF on metal sulfide surface

Abstract

The development of well-organized photocatalysts for solar-driven water splitting to produce hydrogen remains a significant challenge. For the first time, this work investigates a series of dual heterojunctions including metal sulfides (namely CdS, ZnS and Bi₂S₃), and a zirconium-based metal-organic framework (MOF), UiO-67, as potential photocatalysts for hydrogen evolution under solar light. A range of chemical scavengers were employed to facilitate charge carrier separation and enhance photocatalytic activity. The highest hydrogen production rate of 487.5 μmol g⁻¹ h⁻¹ was obtained in the presence of the CdS/UiO-67-NH₂ composite without any cocatalyst and with a hole scavenger triethanolamine (TEOA) for four hours. This report presents the highest hydrogen evolution rate achieved to date within the family of UiO-67-based MOFs, surpassing previously reported values. Notably, neither CdS nor UiO-67-NH₂ exhibited significant hydrogen production individually, suggesting a synergistic effect between the two components. In-depth characterization of the CdS/UiO-67-NH₂ heterojunction revealed the formation of a n-type band alignment, which effectively promotes the separation of photogenerated electron-hole pairs and enhances charge carrier transfer. The findings of this study provide valuable insights into the design and development of advanced MOF-based photocatalysts for solar hydrogen production.