Introduction
Covalent organic frameworks (COFs) are promising photocatalysts due to their excellent visible light absorption, large surface area, and high chemical stability. However, their photocatalytic activity is often limited by the rapid recombination of photogenerated electron–hole pairs. In this study, we aimed to enhance hydrogen production activity by constructing a heterojunction between TpTSN-COF and Copper-doped ZnIn2S4.
Methods
Synthesis of TpTSN-COF/Cu-doped ZIS: The prepared Cu-doped ZIS was added to a mixture of dioxane, mesitylene, and acetic acid and then sonicated. Tp (1,3,5-triformylphloroglucinol) and TSN (o-Tolidine Sulfone) were subsequently added, and hydrothermal synthesis was performed. The resulting product was designated x%-TpTSN-COF/ Cu-doped ZIS, where x% indicates the weight ratio of TpTSN-COF to Cu-doped ZIS.
Hydrogen production test: A Pyrex reactor was charged with a photocatalyst, distilled water, sodium ascorbate (as a sacrificial agent), HCl (for pH adjustment), and H₂PtCl₆ (as a co-catalyst). Before light irradiation, the reaction system was purged with N₂ gas to remove any dissolved oxygen. An LED lamp (450 nm) was used as the light source, and the hydrogen production rate was calculated based on the amount of hydrogen production after 3 hours.
Results
The hydrogen production experiments were conducted with different ratios of TpTSN-COF and Cu-doped ZIS. As a result, 5%-TpTSN-COF/Cu-doped ZIS exhibited the highest hydrogen production rate of 40,000 μmol/g·h, which was approximately 1.5 times higher than that of TpTSN-COF and Cu-doped ZIS individually. The characterization revealed that the increased activity was attributed to improvements in light absorption, charge transfer properties, and an increase in the surface area.
Conclusions
The novel hybridized photocatalyst, TpTSN-COF/ Cu-doped ZIS, was successfully synthesized. The optimal photocatalyst (5%-TpTSN-COF/Cu-doped ZIS) showed approximately 1.5 times higher activity than that of TpTSN-COF and Cu-doped ZIS individually, and this increased activity was attributed to improvements in light absorption, charge transfer properties, and an increase in the surface area.
