Fast Microwave Synthesis of Gold-Doped TiO2 Assisted by Modified Cyclodextrins for Photocatalytic Degradation of Dye and Hydrogen Production

Cécile Machut,Ahmed Addad,Nicolas Kania,Anne Ponchel,Eric Monflier,Bastien Léger,Sébastien Noël,Frédéric Wyrwalski

doi:10.3390/catal10070801

Abstract

A convenient and fast microwave synthesis of gold-doped titanium dioxide materials was developed with the aid of commercially available and common cyclodextrin derivatives, acting both as reducing and stabilizing agents. Anatase titanium oxide was synthesized from titanium chloride by microwave heating without calcination. Then, the resulting titanium oxide was decorated by gold nanoparticles thanks to a microwave-assisted reduction of HAuCl4 by cyclodextrin in alkaline conditions. The materials were fully characterized by UV-Vis spectroscopy, X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and N2 adsorption-desorption measurements, while the metal content was determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The efficiency of the TiO2@Au materials was evaluated with respect to two different photocatalytic reactions, such as dye degradation and hydrogen evolution from water.

Highlights

During the past decades, photocatalysis received extensive research interest for both limiting toxic wastes and developing clean and renewable sources of energy
In order to overcome these drawbacks and improve the photocatalytic performance of semiconductors, one of the promising strategies consists in introducing noble metals at the surface of TiO2, such as gold nanoparticles [7]
The hydroxypropylated β-cyclodextrin (HP-β-CD) to stabilize Au NPs. We focused on these two CDs because of their high solubility in water and their beneficial effect on previously described gold-doped TiO2 [22]

Summary

Introduction

Photocatalysis received extensive research interest for both limiting toxic wastes and developing clean and renewable sources of energy. Its large band gap (3.2 eV) combined with a high recombination rate of the photogenerated electron/hole pairs (e− /h+ ) reduce the photon-to-charge carriers conversion efficiency, and limit the use in photochemical applications under visible or solar light. In order to overcome these drawbacks and improve the photocatalytic performance of semiconductors, one of the promising strategies consists in introducing noble metals at the surface of TiO2 , such as gold nanoparticles [7]. The combination with gold nanoparticles aims at inhibiting the electron-hole pair recombination by trapping electrons and facilitating the transfer of holes on the TiO2 surface [8]. Gold nanoparticles (Au NPs) are known to enhance the activity

Methods

Discussion

Conclusion