Synthesis and Photocatalytic Applications of TiO₂-CQDs Nanocomposites Prepared by Biological Methods

Authors

Maryam S. Jabbar, Department of Physics, College of Science, University of Diyala, Diyala, IraqFollow
Olfat A. Mahmood, Department of Physics, College of Science, University of Diyala, Diyala, IraqFollow
Zainab N. Jameel, Communication Engineering Department, University of Technology, Baghdad, IraqFollow
Noor J. Jihad, Communication Engineering Department, University of Technology, Baghdad, IraqFollow

Abstract

In this study, CQDs were synthesized by the green method using orange juice and ethanol, confused at a relatively low temperature by hydrothermal carbonization process, TiO₂ were prepared by a facile sol-gel method, and TiO₂-CQDs nanocomposites with different weight ratios were prepared by slipe mixing and heat treatment. XRD showed that the CQDs exhibited a broad peak at (002) with hexagonal structure, and TiO₂ (anatase phase) had a polycrystalline nature with tetragonal structure. The FESEM results showed the formation of nanostructures with different shapes and small average particle size. High-resolution transmission electron microscopy revealed that the TiO₂ (anatase phase) agglomerated in mostly spherical shapes and sizes less than 15 nm. The CQDs had a relatively uniform diameter, a spherical shape with a highly crystalline structure, and a size below 5 nm. The FTIR spectra of TiO₂ NPs, CQDs, and TiO₂-CQDs nanocomposite showed the presence of a broad band at 450–4000 cm^–1, which corresponded to the stretching vibration of terminating hydroxyl groups in samples. The results of UV-visible spectroscopy showed that the absorbance of TiO₂-CQDs nanocomposite increased with the increase in the CQDs rate, and the optical energy band gap of TiO₂ and CQDs was 3.14 ev and 3.07 eV, respectively. The energy band gap values of TiO₂-CQDs nanocomposite decreased with the increase in the CQDs rate in the range of (2.72–1.85) eV. The performance of the Photocatalytic was shown by decreasing methylene blue (MB) and methyl orange (MO) under UV irradiation. The results showed that the TiO₂-CQDs nanocomposite with different weight ratios had higher photocatalytic efficiency than TiO₂ NPs, and the photocatalytic efficiency increased with the increase in the CQDs rate. The degradation efficiencies of MB and MO were high at 84% and 39% within 240 min, respectively.

Keywords

Anatase, Carbon quantum dots (CQDs), Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HRTEM), Titanium oxide (TiO2), X-Ray diffraction (XRD)

Subject Area

Physics

Article Type

Article

First Page

923

Last Page

937

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

How to Cite this Article

Jabbar, Maryam S.; Mahmood, Olfat A.; Jameel, Zainab N.; and Jihad, Noor J. (2025) "Synthesis and Photocatalytic Applications of TiO₂-CQDs Nanocomposites Prepared by Biological Methods," Baghdad Science Journal: Vol. 22: Iss. 3, Article 18.
DOI: https://doi.org/10.21123/bsj.2024.9549