Influence of the Deposition Parameters on the Properties of TiO<sub>2</sub> Thin Films on Spherical Substrates
Wastewater treatment targeting reuse may limit water scarcity. Photocatalysis is an advanced oxidation process that may be employed in the removal of traces of organic pollutants, where the material choice is important. Titanium dioxide (TiO<sub>2</sub>) is a highly efficient photocataly...
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MDPI AG
2023-07-01
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| Online Access: | https://www.mdpi.com/1996-1944/16/14/4899 |
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| author | Maria Covei Cristina Bogatu Silvioara Gheorghita Anca Duta Hermine Stroescu Madalina Nicolescu Jose Maria Calderon-Moreno Irina Atkinson Veronica Bratan Mariuca Gartner |
| author_facet | Maria Covei Cristina Bogatu Silvioara Gheorghita Anca Duta Hermine Stroescu Madalina Nicolescu Jose Maria Calderon-Moreno Irina Atkinson Veronica Bratan Mariuca Gartner |
| author_sort | Maria Covei |
| collection | DOAJ |
| description | Wastewater treatment targeting reuse may limit water scarcity. Photocatalysis is an advanced oxidation process that may be employed in the removal of traces of organic pollutants, where the material choice is important. Titanium dioxide (TiO<sub>2</sub>) is a highly efficient photocatalyst with good aqueous stability. TiO<sub>2</sub> powder has a high surface area, thus allowing good pollutant adsorption, but it is difficult to filter for reuse. Thin films have a significantly lower surface area but are easier to regenerate and reuse. In this paper, we report on obtaining sol-gel TiO<sub>2</sub> thin films on spherical beads (2 mm diameter) with high surface area and easy recovery from wastewater. The complex influence of the substrate morphology (etched up to 48 h in concentrated H<sub>2</sub>SO<sub>4</sub>), of the sol dilution with ethanol (1:0 or 1:1), and the number of layers (1 or 2) on the structure, morphology, chemical composition, and photocatalytic performance of the TiO<sub>2</sub> thin films is investigated. Etching the substrate for 2 h in H<sub>2</sub>SO<sub>4</sub> leads to uniform, smooth surfaces on which crystalline, homogeneous TiO<sub>2</sub> thin films are grown. Films deposited using an undiluted sol are stable in water, with some surface reorganization of the TiO<sub>2</sub> aggregates occurring, while the films obtained using diluted sol are partially washed out. By increasing the film thickness through the deposition of a second layer, the roughness increases (from ~50 nm to ~100 nm), but this increase is not high enough to promote higher adsorption or overall photocatalytic efficiency in methylene blue photodegradation (both about 40% after 8 h of UV-Vis irradiation at 55 W/m<sup>2</sup>). The most promising thin film, deposited on spherical bead substrates (etched for 2 h in H<sub>2</sub>SO<sub>4</sub>) using the undiluted sol, with one layer, is highly crystalline, uniform, water-stable, and proves to have good photocatalytic activity. |
| first_indexed | 2024-03-11T00:52:31Z |
| format | Article |
| id | doaj.art-1670bfd43ef749b9ba93e2436e6e0f01 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-11T00:52:31Z |
| publishDate | 2023-07-01 |
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| record_format | Article |
| series | Materials |
| spelling | doaj.art-1670bfd43ef749b9ba93e2436e6e0f012023-11-18T20:14:44ZengMDPI AGMaterials1996-19442023-07-011614489910.3390/ma16144899Influence of the Deposition Parameters on the Properties of TiO<sub>2</sub> Thin Films on Spherical SubstratesMaria Covei0Cristina Bogatu1Silvioara Gheorghita2Anca Duta3Hermine Stroescu4Madalina Nicolescu5Jose Maria Calderon-Moreno6Irina Atkinson7Veronica Bratan8Mariuca Gartner9Department of Product Design, Mechatronics and Environment, Transilvania University of Brasov, 29 Eroilor Bd., 500036 Brasov, RomaniaDepartment of Product Design, Mechatronics and Environment, Transilvania University of Brasov, 29 Eroilor Bd., 500036 Brasov, RomaniaDepartment of Product Design, Mechatronics and Environment, Transilvania University of Brasov, 29 Eroilor Bd., 500036 Brasov, RomaniaDepartment of Product Design, Mechatronics and Environment, Transilvania University of Brasov, 29 Eroilor Bd., 500036 Brasov, Romania“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei St., 060021 Bucharest, Romania“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei St., 060021 Bucharest, Romania“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei St., 060021 Bucharest, Romania“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei St., 060021 Bucharest, Romania“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei St., 060021 Bucharest, Romania“Ilie Murgulescu” Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei St., 060021 Bucharest, RomaniaWastewater treatment targeting reuse may limit water scarcity. Photocatalysis is an advanced oxidation process that may be employed in the removal of traces of organic pollutants, where the material choice is important. Titanium dioxide (TiO<sub>2</sub>) is a highly efficient photocatalyst with good aqueous stability. TiO<sub>2</sub> powder has a high surface area, thus allowing good pollutant adsorption, but it is difficult to filter for reuse. Thin films have a significantly lower surface area but are easier to regenerate and reuse. In this paper, we report on obtaining sol-gel TiO<sub>2</sub> thin films on spherical beads (2 mm diameter) with high surface area and easy recovery from wastewater. The complex influence of the substrate morphology (etched up to 48 h in concentrated H<sub>2</sub>SO<sub>4</sub>), of the sol dilution with ethanol (1:0 or 1:1), and the number of layers (1 or 2) on the structure, morphology, chemical composition, and photocatalytic performance of the TiO<sub>2</sub> thin films is investigated. Etching the substrate for 2 h in H<sub>2</sub>SO<sub>4</sub> leads to uniform, smooth surfaces on which crystalline, homogeneous TiO<sub>2</sub> thin films are grown. Films deposited using an undiluted sol are stable in water, with some surface reorganization of the TiO<sub>2</sub> aggregates occurring, while the films obtained using diluted sol are partially washed out. By increasing the film thickness through the deposition of a second layer, the roughness increases (from ~50 nm to ~100 nm), but this increase is not high enough to promote higher adsorption or overall photocatalytic efficiency in methylene blue photodegradation (both about 40% after 8 h of UV-Vis irradiation at 55 W/m<sup>2</sup>). The most promising thin film, deposited on spherical bead substrates (etched for 2 h in H<sub>2</sub>SO<sub>4</sub>) using the undiluted sol, with one layer, is highly crystalline, uniform, water-stable, and proves to have good photocatalytic activity.https://www.mdpi.com/1996-1944/16/14/4899TiO<sub>2</sub> thin filmphotocatalysisglass bead substratesol-geldilution rationumber of layers |
| spellingShingle | Maria Covei Cristina Bogatu Silvioara Gheorghita Anca Duta Hermine Stroescu Madalina Nicolescu Jose Maria Calderon-Moreno Irina Atkinson Veronica Bratan Mariuca Gartner Influence of the Deposition Parameters on the Properties of TiO<sub>2</sub> Thin Films on Spherical Substrates Materials TiO<sub>2</sub> thin film photocatalysis glass bead substrate sol-gel dilution ratio number of layers |
| title | Influence of the Deposition Parameters on the Properties of TiO<sub>2</sub> Thin Films on Spherical Substrates |
| title_full | Influence of the Deposition Parameters on the Properties of TiO<sub>2</sub> Thin Films on Spherical Substrates |
| title_fullStr | Influence of the Deposition Parameters on the Properties of TiO<sub>2</sub> Thin Films on Spherical Substrates |
| title_full_unstemmed | Influence of the Deposition Parameters on the Properties of TiO<sub>2</sub> Thin Films on Spherical Substrates |
| title_short | Influence of the Deposition Parameters on the Properties of TiO<sub>2</sub> Thin Films on Spherical Substrates |
| title_sort | influence of the deposition parameters on the properties of tio sub 2 sub thin films on spherical substrates |
| topic | TiO<sub>2</sub> thin film photocatalysis glass bead substrate sol-gel dilution ratio number of layers |
| url | https://www.mdpi.com/1996-1944/16/14/4899 |
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