Controlled Synthesis of Hollow α-Fe2O3 Microspheres Assembled With Ionic Liquid for Enhanced Visible-Light Photocatalytic Activity.

Hang Yin,Qingsong Hua,Yuling Zhao,Yunze Long,Yuansai Zhang,Fengyun Wang,Jianmin Zhang,Jie Tang,Xijin Xu

doi:10.3389/fchem.2019.00058

Abstract

Porous self-assembled α-Fe2O3 hollow microspheres were fabricated via an ionic liquid-assisted solvothermal reaction and sequential calcinations. The concentration of the ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate [C4Mim]BF4) was found to play a crucial role in the control of these α-Fe2O3 hollow structures. Trace amounts ionic liquid was used as the soft template to synthesize α-Fe2O3 hollow spheres with a large specific surface (up to 220 m2/g). Based on time-dependent experiments, the proposed formation mechanisms were presented. Under UV light irradiation, the as-synthesized α-Fe2O3 hollow spheres exhibited excellent photocatalysis in Rhodamine B (RhB) photodegradation and the rate constant was 2–3 times higher than α-Fe2O3 particles. The magnetic properties of α-Fe2O3 hollow structures were found to be closely associated with the shape anisotropy.

Highlights

Nanostructured oxides with a variety of useful functionalities are widely applied in photocatalysis, energy storage, etc. (Guo et al, 2017; Li et al, 2017; Zhao et al, 2017, 2018)
The X-ray diffraction (XRD) shows that all diffraction peaks can be indexed in α-Fe2O3 (JCPDS 33–0664) with structural parameters of a = b = 5.038 Å, c = 13.749 Å, α = β = 90◦, and γ = 120◦
Porous self-assembled α-Fe2O3 hollow microspheres were successfully prepared via a facile ionic liquid assistant synthesis approach

Summary

Introduction

Nanostructured oxides with a variety of useful functionalities are widely applied in photocatalysis, energy storage, etc. (Guo et al, 2017; Li et al, 2017; Zhao et al, 2017, 2018). Various self-assembled hollow α-Fe2O3 nano/micro-structures have been prepared by different synthetic techniques, including the two-step reaction process (Yu J. et al, 2009), hydrothermal (Xu et al, 2012), and solvothermal approaches (Song et al, 2012; Zhu et al, 2012), thermal oxidation at high temperature (Xie et al, 2010), etc. Song and co-workers proposed a hydrolysis route to synthesis Fe2O3 hierarchical hollow spheres, via a sodium dodecyl benzenesulfonate (SDBS)-assisted hydrolysis α-Fe2O3 Hollow Spheres as Photocatalysts process. These template methods often suffer from a problem: it is difficult to remove the template and surface-active agent completely. It is still necessary to develop a simple route to synthesizing assembled hollow α-Fe2O3 structures

Methods

Results

Conclusion