Photocatalytic properties and optical absorption of zinc ferrite nanometer films

doi:10.1016/j.mseb.2004.04.012

Materials Science and Engineering: B

Volume 112, Issue 1, 15 September 2004, Pages 1-4

https://doi.org/10.1016/j.mseb.2004.04.012 Get rights and content

Abstract

In order to make new nanometer photocatalytic films with a photo activity under visible light and high degradation efficiency, ZnFe₂O₄ films were deposited on a glass substrate by sol–gel method. The morphology of films was examined by atomic force microscopy. The optical absorption of films and the degradation concentration of methyl orange were measured by atomic absorption spectrum. The results show that the absorption band of ZnFe₂O₄ films shift to visible light regions up to a wavelength of 540 nm and the degradation efficiency of ZnFe₂O₄ films is more than 30% under xenon lamp irradiation.

Introduction

Semiconductor photocatalysts play an important role in environment field because they may degrade the organic pollutants. Now, they are applied to sewage treatment, air purification and self-cleaning glass widely [1]. Though the photocatalytic degradation efficiencies of some semiconductors are high, for example, titanium dioxide, the maximum wavelength of absorption band is 387 nm, and it is applied only under ultraviolet light irradiation [2]. Zinc ferrite is a synthesized semiconductor having a spinel crystal structure. It has been purposely designed as a magnetic material [3]. The absorption band of zinc ferrite is wider than that of TiO₂. In this paper, zinc ferrite nanometer films were prepared on glass surface, and its characteristics and photocatalytic properties were studied.

Section snippets

Zinc ferrite films preparation

Zn(CH₃COO)₂ and Fe(NO₃)₃ with a molar ratio of 1:2 have been added to 10 ml absolute alcohol. After being solved thoroughly, 0.5 ml diethanolamine was added into the solution and stirred for half an hour. After laid for 2 h the solution was spin coated onto a glass plate followed by drying and calcination at different temperatures.

Photodegradation of methyl orange

The distilled water solution of methyl orange was chosen for photodegradation. The concentration is 12 mg/l. A piece of glass plate (the area is 18mm × 18 mm) with zinc

Morphology of films

The morphology of films calcinated at 400–500 °C respectively is shown in Fig. 1. It can be seen that when calcination temperature is 400 °C, the film surface is even, the granules relatively uniform and the diameter of granules is from 30 to 50 nm. When the calcination temperature raises to 500 °C, the granules grow up, and the diameter of some larger granules is near about 100 nm.

Crystalline structure of films

In order to identify the crystalline structure of films, the ZnFe₂O₄ films and ZnFe₂O₄ powder have been examined by

Conclusion

Zinc ferrite films have been prepared on glass surface using a sol–gel method. The surface of films is even. The granules in films relatively uniform. The absorption band of zinc ferrite films is wider than titanium dioxide, which shifts to visible light regions up to a wavelength of 540 nm. When methyl orange solution has been degraded by zinc ferrite films under xenon lamp irradiation, the degradation efficiency is more than 30%. The photocatalytic reactivity varies with the calcination

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