2D/2D Heterojunctions of Layered TiO<sub>2</sub> and (NH<sub>4</sub>)<sub>2</sub>V<sub>3</sub>O<sub>8</sub> for Sunlight-Driven Methylene Blue Degradation
Photocatalysis based on titanium dioxide (TiO<sub>2</sub>) has become a promising method to remediate industrial and municipal effluents in an environmentally friendly manner. However, the efficiency of TiO<sub>2</sub> is hampered by problems such as rapid electron–hole recom...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-07-01
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| Series: | Ceramics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2571-6131/7/3/60 |
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| Summary: | Photocatalysis based on titanium dioxide (TiO<sub>2</sub>) has become a promising method to remediate industrial and municipal effluents in an environmentally friendly manner. However, the efficiency of TiO<sub>2</sub> is hampered by problems such as rapid electron–hole recombination and limited solar spectrum absorption. Furthermore, the sensitization of TiO<sub>2</sub> through heterojunctions with other materials has gained attention. Vanadium, specifically in the form of ammonium vanadate ((NH<sub>4</sub>)<sub>2</sub>V<sub>3</sub>O<sub>8</sub>), has shown promise as a photocatalyst due to its ability to effectively absorb visible light. However, its use in photocatalysis remains limited. Herein, we present a novel synthesis method to produce lamellar (NH<sub>4</sub>)<sub>2</sub>V<sub>3</sub>O<sub>8</sub> as a sensitizer in a supramolecular hybrid photocatalyst of TiO<sub>2</sub>–stearic acid (SA), contributing to a deeper understanding of its structural and magnetic characteristics, expanding the range of visible light absorption, and improving the efficiency of photogenerated electron–hole separation. Materials, such as TiO<sub>2</sub>–SA and (NH<sub>4</sub>)<sub>2</sub>V<sub>3</sub>O<sub>8</sub>, were synthesized and characterized. EPR studies of (NH<sub>4</sub>)<sub>2</sub>V<sub>3</sub>O<sub>8</sub> demonstrated their orientation-dependent magnetic properties and, from measurements of the angular variation of g-values, suggest that the VO<sub>2</sub><sup>+</sup> complexes are in axially distorted octahedral sites. The photocatalytic results indicate that the 2D/2D heterojunction layered TiO<sub>2</sub>/vanadate at a ratio (1:0.050) removed 100% of the methylene blue, used as a model contaminant in this study. The study of the degradation mechanism of methylene blue emphasizes the role of reactive species such as hydroxyl radicals (<sup>•</sup>OH) and superoxide ions (O<sub>2</sub><sup>•−</sup>). These species are crucial for breaking down contaminant molecules, leading to their degradation. The band alignment between ammonium vanadate ((NH<sub>4</sub>)<sub>2</sub>V<sub>3</sub>O<sub>8</sub>) and TiO<sub>2</sub>–SA, shows effective separation and charge transfer processes at their interface. Furthermore, the study confirms the chemical stability and recyclability of the TiO<sub>2</sub>–SA/(NH<sub>4</sub>)<sub>2</sub>V<sub>3</sub>O<sub>8</sub> photocatalyst, demonstrated that it could be used for multiple photocatalytic cycles without a significant loss of activity. This stability, combined with its ability to degrade organic pollutants under solar irradiation, means that the TiO<sub>2</sub>–SA/(NH<sub>4</sub>)<sub>2</sub>V<sub>3</sub>O<sub>8</sub> photocatalyst is a promising candidate for practical environmental remediation applications. |
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| ISSN: | 2571-6131 |