The effect of synthesis method on the structure,and magnetic and photocatalytic properties of hematite (α-Fe2O3) nanoparticles - research article

Ibrahim Abdulkadir,Hafiz M.I Abdallah,Sreekantha B Jonnalagadda,Bice S Martincigh

doi:10.17159/0379-4350/2018/v71a9

Ibrahim Abdulkadir, Hafiz M.I Abdallah + Show 2 more

Open Access

https://doi.org/10.17159/0379-4350/2018/v71a9

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Abstract

Samples of hematite (α-Fe 2 O 3 ) nanoparticles have been synthesized through the co-precipitation route in cetyltrimethylammoniumbromide (Hem_PR), via a citric acid sol-gel method (Hem_SG) and a modified sol-gel method inTween20 (Hem_TW), and each were annealed at three different temperatures (400, 500 and 600 °C). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission and high-resolution electron microscopy (TEM and HRTEM), Mossbauer spectroscopy and by means of a vibrating sample magnetometer (VSM). In addition, the photocatalytic behaviour of each sample was tested on the degradation of rhodamine B (RhB) in solution. All the characterization techniques showed the formation of phases of pure hematite nanoparticles with improved crystallinity after higher temperature annealing. However, the nanoparticles synthesized in Tween 20 showed the smallest particle size and highest BET surface area, saturation magnetization and photocatalytic activity. Of particular note was the ability of Tween 20 to control the growth of the particles so that grain sizes well below 10 nm were obtained. Thus, Tween 20, when used as a surfactant in the sol-gel route, can serve to improve the physical properties of synthesized hematite nanoparticles. Keywords: Hematite, nanoparticles, Mossbauer spectroscopy, magnetic properties, Tween 20, photocatalysis

Highlights

IntroductionA-Fe2O3, is the most thermodynamically stable of all the known iron oxides
Hematite, a-Fe2O3, is the most thermodynamically stable of all the known iron oxides
In this work hematite was synthesized by three different routes, namely: the goethite route in cetyltrimethylammonium bromide (CTAB), the sol-gel route in citric acid, and the modified sol-gel route in Tween 20

Summary

Introduction

A-Fe2O3, is the most thermodynamically stable of all the known iron oxides. It is expected that by using a different reaction medium or adding a surfactant in the preparation process might influence some of the physical properties (e.g. size, porosity, surface area) of the nanoparticles.[20,21]. Hematite nanoparticles were prepared by means of three different routes, namely; (i) chemical precipitation in a cetyltrimethylammonium bromide (CTAB) solution, (ii) a sol-gel method in citric acid solution, and (iii) a sol-gel type method in the presence of the surfactant Tween 20, with a view to study and compare the structure, and magnetic, as well as photocatalytic properties of the products that would be obtained from the first two processes and the one from the Tween 20 medium. Tween 20 may be better at incorporating some water or carbon atoms into the materials, which would help in limiting grain size as well as provide the pores that are needed for higher surface area once the material is calcined.[25,26]

Experimental

Synthesis

Results and Discussion

Magnetic Properties Figure 6 shows the room temperature magnetization curves

Conclusions