Au Modified F-TiO2 for Efficient Photocatalytic Synthesis of Hydrogen Peroxide.

Lijuan Li,Xiaoqiu Zhang,Guifu Zuo,Liwei Feng,Xianguang Meng,Qiannan Zhao,Bingdong Li,Yuqian Zhang

doi:10.3390/molecules26133844

Abstract

In this work, Au-modified F-TiO2 is developed as a simple and efficient photocatalyst for H2O2 production under ultraviolet light. The Au/F-TiO2 photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H2O2 synthesis, as in a pure TiO2 reaction system. The F− modification inhibits the H2O2 decomposition through the formation of the ≡Ti–F complex. Au is an active cocatalyst for photocatalytic H2O2 production. We compared the activity of TiO2 with F− modification and without F− modification in the presence of Au, and found that the H2O2 production rate over Au/F-TiO2 reaches four times that of Au/TiO2. In situ electron spin resonance studies have shown that H2O2 is produced by stepwise single-electron oxygen reduction on the Au/F-TiO2 photocatalyst.

Highlights

Hydrogen peroxide (H2O2) is widely used as a clean oxidant in environmental purification and organic synthesis [1,2]
Many semiconductor materials with UV and visible light activities, such as ZnO [6,7], C3N4 [8,9,10], BiVO4 [11], and TiO2 [12,13,14,15,16,17,18] have demonstrated the potential for direct synthesis of H2O2
In order to solve these problems, we developed F−-modified TiO2 by a hydrothermal method instead of adding NaF in the photocatalytic reaction medium and used Au as the cocatalyst of F-TiO2

Summary

Introduction

Hydrogen peroxide (H2O2) is widely used as a clean oxidant in environmental purification and organic synthesis [1,2]. Many semiconductor materials with UV and visible light activities, such as ZnO [6,7], C3N4 [8,9,10], BiVO4 [11], and TiO2 [12,13,14,15,16,17,18] have demonstrated the potential for direct synthesis of H2O2 When these semiconductors are loaded with appropriate cocatalysts, the photocatalytic activity of the catalysts could be greatly improved. Maurino et al [20] reported that the production of H2O2 increased remarkably after adding fluoride into the reaction suspension of TiO2 These studies showed the competition of the F− with superoxide/peroxide species for the surface sites of TiO2. The ≡Ti–F formation decreases the amount of ≡Ti–OOH and inhibits H2O2 degradation This method is interesting but it will cause fluoride pollution to the reaction medium and the difficulty of H2O2 purification. In situ ESR reveals that the H2O2 is efficiently formed through a stepwise single-electron ORR process on the Au/F-TiO2 photocatalyst

Experimental Materials Preparation

Material Characterization

Photocatalytic Activity Test

In Situ ESR Test

Conclusions