Photocatalytic degradation of methylene blue at nanostructured ZnO thin films
Publikation: Beitrag in Fachzeitschrift › Forschungsartikel › Beigetragen › Begutachtung
Beitragende
Abstract
The photocatalytic degradation of the wastewater dye pollutant methylene blue (MB) at ZnO nanostructured porous thin films, deposited by direct current (DC) reactive magnetron sputtering (RMS) on Si substrates, was studied. It was observed that over 4 photocatalytic cycles (0.3 mg/L MB solution, 540 min UV irradiation) the rate constant k of MB degradation decreased by ~50%, varying in the range (1.54 ÷ 0.78) · 10-9 (mol·L-1·min-1). For a deeper analysis of the photodegradation mechanism, detailed information on the nanostructured ZnO surface morphology and local surface and subsurface chemistry (nonstoichiometry) were obtained by using Scanning Electron Microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) as complementary analytical methods. The SEM studies revealed that at the surface of the nanostructured ZnO thin films a coral reef structure containing polycrystalline coral dendrites is present, and that, after the photocatalytic experiments, the sizes of individual crystallites increased, varying in the range 43 ÷ 76 nm for the longer axis, and in the range 28 ÷ 58 nm for the shorter axis. In turn, the XPS studies showed a slight non-stoichiometry, mainly defined by the relative [O]/[Zn] concentration of ca. 1.4, whereas [C]/[Zn] was ca. 1.2, both before and after the photocatalytic experiments. This phenomenon was directly related to the presence of superficial ZnO lattice oxygen atoms that can participate in the oxidation of the adsorbed MB molecules, as well as the presence of surface hydroxyl groups acting as hole-acceptors to produce OH· radicals, which can be responsible for the generation of superoxide ions. In addition, after experiments, the XPS measurements revealed the presence of carboxyl and carbonyl functional groups, ascribable to the oxidation by-products formed during the photodegradation of MB.
Details
Originalsprache | Englisch |
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Aufsatznummer | 155702 |
Seitenumfang | 11 |
Fachzeitschrift | Nanotechnology |
Jahrgang | 34 |
Ausgabenummer | 15 |
Publikationsstatus | Veröffentlicht - 9 Apr. 2023 |
Peer-Review-Status | Ja |
Externe IDs
Scopus | 85147093772 |
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PubMed | 36595265 |
Mendeley | f0e30c2e-e305-397e-9309-5e7807fc2e42 |
WOS | 000921694200001 |
Schlagworte
Forschungsprofillinien der TU Dresden
DFG-Fachsystematik nach Fachkollegium
- Theoretische Chemie: Moleküle, Materialien, Oberflächen
- Theoretische Chemie: Elektronenstruktur, Dynamik, Simulation
- Theoretische Physik der kondensierten Materie
- Computergestütztes Werkstoffdesign und Simulation von Werkstoffverhalten von atomistischer bis mikroskopischer Skala
- Herstellung und Eigenschaften von Funktionsmaterialien
- Experimentelle Physik der kondensierten Materie
Fächergruppen, Lehr- und Forschungsbereiche, Fachgebiete nach Destatis
Ziele für nachhaltige Entwicklung
ASJC Scopus Sachgebiete
Schlagwörter
- immobilized photocatalysts, methylene blue, photocatalytic degradation, ZnO thin films nanostructures, Photocatalytic degradation, Immobilized photocatalysts, Methylene blue