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<p>In this study, TiO<sub>2</sub> nanowires/nanotubes (TiO<sub>2</sub> WT) and graphene quantum dots-decorated TiO<sub>2</sub> WT (GQDs/TiO<sub>2</sub> WT) were fabricated using a combination of anodic oxidation and hydrothermal methods. Both TiO<sub>2</sub> WT and GQDs/TiO<sub>2</sub> WT exhibited anatase phase with preferred orientations along the (101), (004), (112), (200), and (105) planes. The TiO<sub>2</sub> WT displayed a well-defined, uniform structure comprising nanotube arrays with an average diameter of ~ 100&#xa0;nm and a length of ~ 4.8&#xa0;μm, covered by nanowires with lengths of 2.5–3.5&#xa0;μm. Amorphous GQDs were successfully decorated onto TiO<sub>2</sub> WT at various loading levels, as confirmed by XRD, SEM, HRTEM, EDS, Raman spectroscopy, and XPS. GQDs/TiO<sub>2</sub> WT demonstrated photocatalytic activity approximately twice as high as TiO<sub>2</sub> WT for degrading methylene blue (MB) and pesticides, including methiocarb (MTC), carbofuran (CBF), and dimethoate (DMT). The photodegradation rates achieved for GQDs-2/TiO<sub>2</sub> WT were 1.336 × 10⁻<sup>2</sup> min<sup>− 1</sup> for MB, 20.3 × 10⁻<sup>2</sup> min<sup>− 1</sup> for CBF, 121 × 10⁻<sup>2</sup> min<sup>− 1</sup> for MTC, and 21.8 × 10⁻<sup>2</sup> min<sup>− 1</sup> for DMT. The enhanced performance was attributed to the synergistic effects of improved photogenerated electron-hole separation and extended light absorption compared to bare TiO<sub>2</sub>. Stability tests over four cycles of MB degradation showed ~ 80% retention of photocatalytic efficiency, indicating excellent reusability and structural stability. These results highlight the potential of GQDs/TiO<sub>2</sub> WT as a robust and efficient photocatalyst for environmental remediation, particularly for degrading organic pollutants and pesticides under UV-Vis illumination.</p>

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Graphene quantum dot-decorated TiO2 nanowires/nanotubes: enhanced photocatalysis for methylene blue and pesticide degradation

  • 期刊论文

  • 发表日期：

    2025年3月21日

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  • Ngo Ngoc Uyen,
  • Ly Anh Tu,
  • Phuoc Huu Le

摘要

In this study, TiO2 nanowires/nanotubes (TiO2 WT) and graphene quantum dots-decorated TiO2 WT (GQDs/TiO2 WT) were fabricated using a combination of anodic oxidation and hydrothermal methods. Both TiO2 WT and GQDs/TiO2 WT exhibited anatase phase with preferred orientations along the (101), (004), (112), (200), and (105) planes. The TiO2 WT displayed a well-defined, uniform structure comprising nanotube arrays with an average diameter of ~ 100 nm and a length of ~ 4.8 μm, covered by nanowires with lengths of 2.5–3.5 μm. Amorphous GQDs were successfully decorated onto TiO2 WT at various loading levels, as confirmed by XRD, SEM, HRTEM, EDS, Raman spectroscopy, and XPS. GQDs/TiO2 WT demonstrated photocatalytic activity approximately twice as high as TiO2 WT for degrading methylene blue (MB) and pesticides, including methiocarb (MTC), carbofuran (CBF), and dimethoate (DMT). The photodegradation rates achieved for GQDs-2/TiO2 WT were 1.336 × 10⁻2 min− 1 for MB, 20.3 × 10⁻2 min− 1 for CBF, 121 × 10⁻2 min− 1 for MTC, and 21.8 × 10⁻2 min− 1 for DMT. The enhanced performance was attributed to the synergistic effects of improved photogenerated electron-hole separation and extended light absorption compared to bare TiO2. Stability tests over four cycles of MB degradation showed ~ 80% retention of photocatalytic efficiency, indicating excellent reusability and structural stability. These results highlight the potential of GQDs/TiO2 WT as a robust and efficient photocatalyst for environmental remediation, particularly for degrading organic pollutants and pesticides under UV-Vis illumination.