Preparation and characterization of ZIF-67/ TiO₂) thin film

• Main Author: Khoo, Lenny
• Format: Academic Exercise
• Language: English
• Published: 2015
• Subjects: QD Chemistry
• Online Access: https://eprints.ums.edu.my/id/eprint/17744/1/Preparation%20and%20characterization.pdf; https://eprints.ums.edu.my/id/eprint/17744/
• Institution: Universiti Malaysia Sabah

Titanium dioxide (TiO₂) is one of the most widely used photocatalyst due to its nontoxic, low cost, good chemical stability, elemental abundance, and photocatalytic properties. But there are some problems faced by TiO₂ first is that if TiO₂ used is in the powder form an additional separation process is needed to separate the TiO₂ particles from the wastewater after the treatment. TiO₂ has a high bandgap which requires UV-A light to activate it. The high recombination rate of electron hole pair occurs before the photocatalytic process starts. ZIF-67 is well known for its porosity properties. It is used in this study to act as an adsorbent to adsorb organic dye on the surface of TiO₂ to allow photodegradation to occur and at the same time forming synergetic effect with TiO₂ to reduce its band gap from UV region to visible light region. ZIF-67/TiO₂ thin film is form by using dip-coating method. The morphology of ZIF-67/TiO₂ is observed by using SEM. A square-like shape of ZIF-67 is observed on the surface of TiO₂ thin film. The photodegradation result obtained show that ZIF- 67/TiO₂ (43.63%) has a lower photodegradation efficiency than un-doped TiO₂ (58.81%) under the irradiation of UV-A light. This shows that ZIF-67 does not enhance the photocatalytic ability of TiO₂ under irradiation of UV-A light. This may cause by the combination of ZIF-67 with the Co-doped TiO₂ thin film does not show a synergetic effect in photodegradation. Besides that, ZIF-67 does not overcome the high recombination rate of electron hole pair of TiO₂ by adsorbing MB longer on the surface. But from this study shows that cobalt can act as a dopant to enhance the photocatalytic properties of TiO₂ in the visible light region. Co-doped TiO₂ shows a photodegradation efficiency of 25.27 % compared to un-doped TiO₂ which is only 14.36%.