Incorporation of NiO into SiO2, TiO2, Al2O3, and Na4.2Ca2.8(Si6O18) matrices: medium effect on the optical properties and catalytic degradation of methylene blue
Author
dc.contributor.author
Alvarado Díaz, Carlos
Author
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Valenzuela, María L.
Author
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Cifuentes Vaca, Olga
Author
dc.contributor.author
Segovia, Marjorie
Author
dc.contributor.author
Laguna Bercero, Miguel A.
Admission date
dc.date.accessioned
2021-06-24T22:58:26Z
Available date
dc.date.available
2021-06-24T22:58:26Z
Publication date
dc.date.issued
2020
Cita de ítem
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Nanomaterials 2020, 10, 2470
es_ES
Identifier
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10.3390/nano10122470
Identifier
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https://repositorio.uchile.cl/handle/2250/180271
Abstract
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The medium effect of the optical and catalytic degradation of methylene blue was studied in the NiO/SiO2, NiO/TiO2, NiO/Al2O3, and NiO/Na4.2Ca2.8(Si6O18) composites, which were prepared by a solid-state method. The new composites were characterized by XRD (X-ray diffraction of powder), SEM/EDS, TEM, and HR-TEM. The size of the NiO nanoparticles obtained from the PSP-4-PVP (polyvinylpyrrolidone) precursors inside the different matrices follow the order of SiO2 > TiO2 > Al2O3. However, NiO nanoparticles obtained from the chitosan precursor does not present an effect on the particle size. It was found that the medium effect of the matrices (SiO2, TiO2, Al2O3, and Na4.2Ca2.8(Si6O18)) on the photocatalytic methylene blue degradation, can be described as a specific interaction of the NiO material acting as a semiconductor with the MxOy materials through a possible p-n junction. The highest catalytic activity was found for the TiO2 and glass composites where a favorable p-n junction was formed. The isolating character of Al2O3 and SiO2 and their non-semiconductor behavior preclude this interaction to form a p-n junction, and thus a lower catalytic activity. NiO/SiO2 and NiO/Na4.2Ca2.8(Si6O18) showed a similar photocatalytic behavior. On the other hand, the effect of the matrix on the optical properties for the NiO/SiO2, NiO/TiO2, NiO/Al2O3, and NiO/Na4.2Ca2.8(Si6O18) composites can be described by the different dielectric constants of the SiO2, TiO2, Al2O3, Na4.2Ca2.8(Si6O18) matrices. The maxima absorption of the composites (lambda(max)) exhibit a direct relationship with the dielectric constants, while their semiconductor bandgap (E-g) present an inverse relationship with the dielectric constants. A direct relationship between lambda(max) and E-g was found from these correlations. The effect of the polymer precursor on the particle size can explain some deviations from this relationship, as the correlation between the particle size and absorption is well known. Finally, the NiO/Na4.2Ca2.8(Si6O18) composite was reported in this work for the first time.
es_ES
Patrocinador
dc.description.sponsorship
Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)
CONICYT FONDECYT
1160241
Spanish Government
PID2019-107106RB-C32
Incorporation of NiO into SiO2, TiO2, Al2O3, and Na4.2Ca2.8(Si6O18) matrices: medium effect on the optical properties and catalytic degradation of methylene blue