Synthesis Design of Electronegativity Dependent WO<sub>3</sub> and WO<sub>3</sub>∙0.33H<sub>2</sub>O Materials for a Better Understanding of TiO<sub>2</sub>/WO<sub>3</sub> Composites’ Photocatalytic Activity
The design of a semiconductor or a composite semiconductor system—with applications in materials science—is complex because its morphology and structure depend on several parameters. These parameters are the precursor type, solvent, pH of the solution, synthesis approach, or shaping agents. This stu...
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MDPI AG
2021-06-01
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| author | István Székely Endre-Zsolt Kedves Zsolt Pap Monica Baia |
| author_facet | István Székely Endre-Zsolt Kedves Zsolt Pap Monica Baia |
| author_sort | István Székely |
| collection | DOAJ |
| description | The design of a semiconductor or a composite semiconductor system—with applications in materials science—is complex because its morphology and structure depend on several parameters. These parameters are the precursor type, solvent, pH of the solution, synthesis approach, or shaping agents. This study gives meaningful insight regarding the synthesis design of such WO<sub>3</sub> materials. By systematically alternating the precursor (sodium tungstate dihydrate—NWH, or ammonium tungstate hydrate—AMT), subsequently shaping the agents (halide salts—NaX, KX, or hydrohalic acids—HX; X = F<sup>−</sup>, Cl<sup>−</sup>, Br<sup>−</sup>, I<sup>−</sup>), we have obtained WO<sub>3</sub> semiconductors by hydrothermal treatment, which in composite systems can enhance the commercial TiO<sub>2</sub> photocatalytic activity. We investigated three sample series: WO<sub>3</sub>-NWH-NaX/WO<sub>3</sub>-NWH-KX and, subsequently, WO<sub>3</sub>-AMT-HX. The presence of W<sup>+5</sup> centers was evidenced by Raman and X-ray photoelectron spectroscopy. W<sup>+5</sup> and W<sup>+6</sup> species affected the band gap values of the NaX and KX series; a higher percentage of W<sup>+5</sup> and, subsequently, W<sup>+6</sup> caused a redshift, while, regarding the HX series, it led to a blue shift. Increased electronegativity of the halide anions has an unfavorable effect on the composites’ photoactivity. In contrast, in the case of hydrohalic acids, it had a positive impact. |
| first_indexed | 2024-03-09T04:49:40Z |
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| last_indexed | 2024-03-09T04:49:40Z |
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| spelling | doaj.art-3cdf01b888b242b98e82d8d1f6520e772023-12-03T13:11:15ZengMDPI AGCatalysts2073-43442021-06-0111777910.3390/catal11070779Synthesis Design of Electronegativity Dependent WO<sub>3</sub> and WO<sub>3</sub>∙0.33H<sub>2</sub>O Materials for a Better Understanding of TiO<sub>2</sub>/WO<sub>3</sub> Composites’ Photocatalytic ActivityIstván Székely0Endre-Zsolt Kedves1Zsolt Pap2Monica Baia3Faculty of Physics, Babeș–Bolyai University, Mihail Kogălniceanu Str. 1, RO-400084 Cluj-Napoca, RomaniaFaculty of Physics, Babeș–Bolyai University, Mihail Kogălniceanu Str. 1, RO-400084 Cluj-Napoca, RomaniaInterdisciplinary Research Institute on Bio-Nano-Sciences, Babeș-Bolyai University, Treboniu Laurian Str. 42, RO-400271 Cluj-Napoca, RomaniaFaculty of Physics, Babeș–Bolyai University, Mihail Kogălniceanu Str. 1, RO-400084 Cluj-Napoca, RomaniaThe design of a semiconductor or a composite semiconductor system—with applications in materials science—is complex because its morphology and structure depend on several parameters. These parameters are the precursor type, solvent, pH of the solution, synthesis approach, or shaping agents. This study gives meaningful insight regarding the synthesis design of such WO<sub>3</sub> materials. By systematically alternating the precursor (sodium tungstate dihydrate—NWH, or ammonium tungstate hydrate—AMT), subsequently shaping the agents (halide salts—NaX, KX, or hydrohalic acids—HX; X = F<sup>−</sup>, Cl<sup>−</sup>, Br<sup>−</sup>, I<sup>−</sup>), we have obtained WO<sub>3</sub> semiconductors by hydrothermal treatment, which in composite systems can enhance the commercial TiO<sub>2</sub> photocatalytic activity. We investigated three sample series: WO<sub>3</sub>-NWH-NaX/WO<sub>3</sub>-NWH-KX and, subsequently, WO<sub>3</sub>-AMT-HX. The presence of W<sup>+5</sup> centers was evidenced by Raman and X-ray photoelectron spectroscopy. W<sup>+5</sup> and W<sup>+6</sup> species affected the band gap values of the NaX and KX series; a higher percentage of W<sup>+5</sup> and, subsequently, W<sup>+6</sup> caused a redshift, while, regarding the HX series, it led to a blue shift. Increased electronegativity of the halide anions has an unfavorable effect on the composites’ photoactivity. In contrast, in the case of hydrohalic acids, it had a positive impact.https://www.mdpi.com/2073-4344/11/7/779tungsten trioxideelectronegativitymorpho-structural propertiesoxygen vacanciessurface defectsphotocatalytic activity |
| spellingShingle | István Székely Endre-Zsolt Kedves Zsolt Pap Monica Baia Synthesis Design of Electronegativity Dependent WO<sub>3</sub> and WO<sub>3</sub>∙0.33H<sub>2</sub>O Materials for a Better Understanding of TiO<sub>2</sub>/WO<sub>3</sub> Composites’ Photocatalytic Activity Catalysts tungsten trioxide electronegativity morpho-structural properties oxygen vacancies surface defects photocatalytic activity |
| title | Synthesis Design of Electronegativity Dependent WO<sub>3</sub> and WO<sub>3</sub>∙0.33H<sub>2</sub>O Materials for a Better Understanding of TiO<sub>2</sub>/WO<sub>3</sub> Composites’ Photocatalytic Activity |
| title_full | Synthesis Design of Electronegativity Dependent WO<sub>3</sub> and WO<sub>3</sub>∙0.33H<sub>2</sub>O Materials for a Better Understanding of TiO<sub>2</sub>/WO<sub>3</sub> Composites’ Photocatalytic Activity |
| title_fullStr | Synthesis Design of Electronegativity Dependent WO<sub>3</sub> and WO<sub>3</sub>∙0.33H<sub>2</sub>O Materials for a Better Understanding of TiO<sub>2</sub>/WO<sub>3</sub> Composites’ Photocatalytic Activity |
| title_full_unstemmed | Synthesis Design of Electronegativity Dependent WO<sub>3</sub> and WO<sub>3</sub>∙0.33H<sub>2</sub>O Materials for a Better Understanding of TiO<sub>2</sub>/WO<sub>3</sub> Composites’ Photocatalytic Activity |
| title_short | Synthesis Design of Electronegativity Dependent WO<sub>3</sub> and WO<sub>3</sub>∙0.33H<sub>2</sub>O Materials for a Better Understanding of TiO<sub>2</sub>/WO<sub>3</sub> Composites’ Photocatalytic Activity |
| title_sort | synthesis design of electronegativity dependent wo sub 3 sub and wo sub 3 sub ∙0 33h sub 2 sub o materials for a better understanding of tio sub 2 sub wo sub 3 sub composites photocatalytic activity |
| topic | tungsten trioxide electronegativity morpho-structural properties oxygen vacancies surface defects photocatalytic activity |
| url | https://www.mdpi.com/2073-4344/11/7/779 |
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