Photocatalytic activity of ZnO nanoparticles and the role of the synthesis method on their physical and chemical properties
In the present study, we report on the effect of the synthesis method in the photoactivity of ZnO-NPs. The nanoparticles were prepared by precipitation and sol-gel procedures using zinc nitrate and zinc (II) acetylacetonate as ZnO precursors, respectively. The obtained samples were named as ZnO-PP (...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/400364 |
| Acceso en línea: | http://hdl.handle.net/10261/400364 https://api.elsevier.com/content/abstract/scopus_id/85090709631 |
| Access Level: | acceso abierto |
| Palabra clave: | ZnO nanoparticles Hydroxyl radicals Oxygen vacancies Phenol degradation Photocatalysis nanoparticles oxygen radicals |
| Sumario: | In the present study, we report on the effect of the synthesis method in the photoactivity of ZnO-NPs. The nanoparticles were prepared by precipitation and sol-gel procedures using zinc nitrate and zinc (II) acetylacetonate as ZnO precursors, respectively. The obtained samples were named as ZnO-PP (precipitation method) and ZnO-SG (sol-gel method). The powders were calcined at 500 °C and further characterized by Fourier Transform Infrared spectroscopy, X-ray Powder Diffraction, N<inf>2</inf> adsorption, thermal analysis, Diffuse Reflectance UV-Vis spectroscopy, and Electron Microscopy. Both methods of synthesis lead to formation of pure ZnO with hexagonal-wurtzite crystalline structures with average crystallite sizes ∼30 nm. The specific surface area was affected by the synthesis method, since S<inf>BET</inf> values were 5 m<sup>2</sup>/g and 13 m<sup>2</sup>/g for sol-gel and precipitation method, respectively. The electron microscopy revealed significant changes in morphology for the obtained nanoparticles, as sol-gel directed the hexagonal rod-like geometries (∼50 nm in diameter) while quasi-spherical nanoparticles (∼100 nm in diameter) were formed using precipitation method. Photocatalytic activity was estimated by degrading phenol (50 ppm) as probe molecule under UVA irradiation (λ = 356 nm), the results demonstrated that ZnO-PP reached 100 % of degradation after 120 min and 90 % of the pollutant was mineralized, whereas for ZnO-SG the results were 80 % and 48 % respectively. Fluorescence test using terephthalic acid (TA) demonstrated higher formation of OH<sup>•</sup> radicals for ZnO synthesized by precipitation method, which could explain the higher photodegradation and mineralization observed. These results support that even slight differences in physical and chemical properties of ZnO, have a significant impact on the photocatalytic performance of such nanoparticles. |
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