Temperature effects on VO2 thin films deposited by RF sputtering for the degradation by photocatalysis of methylene blue and naproxen
Por:
Acosta, Dwight, Magana, Carlos, Hernandez, Francisco, Chavez-Esquivel, Gerardo, Eduardo Cortes-Cordova, Daniel, HUERTA, LAZARO, Uriel Valdes-Martinez, Omar
Publicada:
1 jul 2020
Categoría:
Chemical engineering (miscellaneous)
Resumen:
The temperature effect on VO2 thin films synthesized by RF sputtering on
their morphological, optical, electrical properties and their activity
in the photocatalytic degradation of methylene blue and naproxen was
studied. Characterization results presented microcrystallinity for VO2
films treated at 50 and 100 degrees C. Nevertheless, the untreated films
and films treated at 200 degrees C revealed characteristic peaks of
monoclinic and tetragonal phases. SEM micrographs with elemental mapping
of VO2 films showed granular morphology and a good oxygen dispersion
along the film surface, possibly due to a restructuring on the film
occasioned by particle coalescence and vanadium oxide island
conformation. The electronic transmittance spectra showed the d-d
transition characteristic for the square-pyramidal stereochemistry of
vanadium (IV) ion, where the optical band interval was high for films
treated at 50 degrees C. Raman spectroscopy results presented an
increment in the V = O/V-O ratio as a function of temperature, probably
related to superficial vanadium species formation. X-ray spectroscopy
results showed the Onon-lattice/O-lattice ratio values higher for films
treated at 50 degrees C than the other films, related to an oxide
character. The V 2p fit results presented V4+, V5+ regions and
satellites for VO2 films thermal treated at 50 degrees C. The electrical
resistivity on the VO2 films decreased as a function of temperature.
Finally, the VO2 films thermal treated at 50 degrees C had higher
photocatalytic activity in the degradation of methylene blue and
naproxen compared to the other VO2 films, possibly associated with high
electron mobility between the surface and the bulk, where the oxygen
vacancies act as recombination sites for the e(-)/h(+) pairs during
photocatalytic degradation.
Filiaciones:
Univ Nacl Autonoma Mexico, Inst Fis, Ciudad Univ, Mexico City 04510, DF, Mexico
Univ Autonoma Metropolitana Azcapotzalco, Div Ciencias Basicas & Ingn, Dept Ciencias Basicas, Av San Pablo 180, Mexico City 02200, DF, Mexico
Univ Nacl Autonoma Mexico, Inst Mat, Circuito Exterior S-N,Cuidad Univ, Mexico City 04510, DF, Mexico
Univ Autonoma Metropolitana Iztapalapa, Dept Ingn Proc & Hidraul, Av San Rafael Atlixco 86,Col Leyes Reforma 1a Se, Mexico City 09310, DF, Mexico
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