Photocatalytic activity of non-stoichiometric ZnFe sub(2)O sub(4) under visible light irradiation

Nanostructured zinc ferrites with different excess iron contents (ZnFe sub(2+z)O sub(4), where z = 0.00, 0.05, 0.10 and 0.15) have been synthesized using the sol-gel auto-combustion method. The effect of excess iron on the structural, optical and visible light photocatalytic activity of zinc ferrite...

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Bibliographic Details
Published in:Physica scripta 2014-04, Vol.89 (4), p.1-8
Main Authors: Sutka, A, Parna, R, Kleperis, J, Kaambre, T, Pavlovska, I, Korsaks, V, Malnieks, K, Grinberga, L, Kisand, V
Format: Article
Language:English
Subjects:
Ferrites
Iron
Nanostructure
Photocatalysis
Scanning electron microscopy
X-ray photoelectron spectroscopy
X-rays
Zinc
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Summary:Nanostructured zinc ferrites with different excess iron contents (ZnFe sub(2+z)O sub(4), where z = 0.00, 0.05, 0.10 and 0.15) have been synthesized using the sol-gel auto-combustion method. The effect of excess iron on the structural, optical and visible light photocatalytic activity of zinc ferrite samples has been investigated. X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), x-ray magnetic circular dichroism (XMCD), Brunauer-Emmett-Teller theory, scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV-Vis) and photoluminescence spectroscopy were used to characterize the synthesized non-stoichiometric ZnFe sub(2)O sub(4) powders. The XRD patterns demonstrated that the samples consist of single phase spinel structure with crystallite sizes of ~ 25 nm. SEM analysis indicated that the nanosized particles grow together in porous clusters with a size of several microns. The XPS and XMCD analyses revealed that the excess iron ion substitutes Zn super(2+) in tetrahedral sites and in octahedral sites Fe super(2+) can be found in addition to Fe super(3+), which could be created to restore the overall charge balance in the crystal lattice. Stoichiometric zinc ferrite (ZnFe sub(2+z)O sub(4), z = 0.00) exhibited higher photocatalytic activity (40%) than the excess iron sample (ZnFe sub(2+z)O sub(4), z = 0.15, i.e. 4%) under visible light irradiation for 3 h. This was explained by the formation of Fe super(2+) in the octahedral sites of excess iron ZnFe sub(2)O sub(4); these species act as recombination centres.
ISSN:0031-8949
1402-4896
DOI:10.1088/0031-8949/89/04/044011