Fabrication of Magnetite/Silica/Titania Core-Shell Nanoparticles

Suh Cem Pang,Suk Fun Chin,Sze Yun Kho

doi:10.1155/2012/427310

Abstract

Fe3O4/SiO2/TiO2core-shell nanoparticles were synthesized via a sol-gel method with the aid of sonication. Fe3O4nanoparticles were being encapsulated within discrete silica nanospheres, and a layer of TiO2shell was then coated directly onto each silica nanosphere. As-synthesized Fe3O4/SiO2/TiO2core-shell nanoparticles showed enhanced photocatalytic properties as evidenced by the enhanced photodegradation of methylene blue under UV light irradiation.

Highlights

Over the past decades, titanium dioxide (TiO2) nanoparticles have gained much attention as a photocatalyst and catalyst support [1, 2]
This is attributed to the SiO2 layer which serves as an insulating layer between Fe3O4 nanoparticles and the TiO2 shell
Fe3O4 nanoparticles were being encapsulated within the SiO2 shells upon the hydrolysis and condensation of TEOS as new bonds of Fe–O–Si were formed between the interface of Fe3O4 and TEOS

Summary

Introduction

Titanium dioxide (TiO2) nanoparticles have gained much attention as a photocatalyst and catalyst support [1, 2]. TiO2 nanoparticles of small mean particle sizes possess high surface area and photocatalytic activity. Much effort has been focused on coating of TiO2 on high surface area supports such as silica or alumina in order to stabilize TiO2 nanoparticles. One of the ways to overcome this problem is to coat TiO2 onto magnetite (Fe3O4) cores and the resulting Fe3O4/TiO2 core-shell nanoparticles can be recovered through manipulation by external magnetic field. It was difficult to achieve complete coating of Fe3O4 nanoparticles with TiO2 at nanometer scale using the sol-gel method. Some researchers had attempted to coat a thin layer of SiO2 between Fe3O4 nanoparticles and TiO2 shell. The presence of a SiO2 layer between TiO2 shell and Fe3O4 nanoparticles could increase the lifetime of photogenerated holes which in turn, resulted in increased photoreactivity [3, 4]. This is attributed to the SiO2 layer which serves as an insulating layer between Fe3O4 nanoparticles (hole-electron trap center) and the TiO2 shell

Methods

Results

Conclusion