磁性核壳结构Fe3O4@SiO2@TiO2-Au的制备及其光催化还原性能
Fabrication of magnetic Fe3O4@SiO2@TiO2-Au with core-shell structure and its photocatalytic reduction activity
郭小华 1马剑琪1
作者信息
- 1. 陕西理工大学 化学与环境科学学院,汉中 723001
- 折叠
摘要
TiO2基的光催化剂已被广泛用于各种有机物污染物的光氧化和水中六价铬Cr(Ⅵ)的光还原.然而,对光催化还原硝基芳香化合物为胺基芳香化合物的研究鲜有报道.本文采用液相沉积(LPD)法将锐钛矿型TiO2沉积在非晶SiO2包覆的Fe3O4上,制备了核壳结构的Fe3O4@SiO2@TiO2磁性光催化剂.为进一步提高其光催化活性,将均匀分散的Au纳米粒子(Au NPs)修饰在其表面,以获得Fe3O4@SiO2@TiO2-Au纳米复合材料.对这两种TiO2基的磁性复合材料进行表征并将其用作光催化剂.在紫外光照射下,用HCOONH4作为空穴捕集剂和H源,以对硝基苯胺(p-NA)光催化还原至对苯二胺(p-PDA)作为模型反应,评价其光催化还原性能.结果表明:虽然两种光催化剂都能将p-NA完全还原成p-PDA,但Fe3O4@SiO2@TiO2-Au表现出比Fe3O4@SiO2@TiO2更优异的光催化活性.这是由于TiO2表面修饰的Au NPs能有效地促进光激发的电子从TiO2的导带转移到Au,最大限度地减少电子和空穴的复合率,延长光电子的寿命.此外,不可或缺的HCOONH4在p-NA的光催化还原中能有效地捕获光生空穴,极大地提高了其光催化还原效率.
Abstract
TiO2-based photocatalysts have been widely used for photoxidation of various organic pollutants and photoreduction of Cr(Ⅵ)in aqueous solution.However,less attention has been paid to the photocatalyzed reduc-tion of nitro group to amino group of nitroaromatics.In this study,liquid-phase deposition(LPD)technique was adopted to deposit anatase TiO2 shell on amorphous SiO2-coated Fe3O4 to form core-shell Fe3O4@SiO2@TiO2 magnetic photocatalyst.To further promote its photocatalytic activity,uniformly dispersed Au nanoparticles(NPs)were decorated on its surface to obtain Fe3O4@SiO2@TiO2-Au composite.Both the TiO2-based magnetic composites were characterized and used as photocatalysts.To evaluate their photocatalytic performance,the photocatalyzed reduction of p-nitroaniline(p-NA)to p-phenylenediamine(p-PDA)was chosen as a model reaction under UV irradiation using HCOONH4 as a hole scavenger and H source.Although p-NA can be com-pletely reduced to p-PDA by the two photocatalysts,Fe3O4@SiO2@TiO2-Au exhibits much superior photocatalytic activity to Fe3O4@SiO2@TiO2.The is because Au NPs decorated on the TiO2 can efficiently facilitate the photo-excited electron-transfer from the conduction band of TiO2 to Au,which is favorable for minimizing the recombina-tion rate of electrons and holes and prolong the lifetime of the photoelectrons.In addition,HCOONH4 plays an indispensable role in improving the photocatalytic reduction of p-NA via capturing photo-generated holes.
关键词
磁性/二氧化钛/核壳结构/Fe3O4@SiO2@TiO2-Au/光催化还原/对硝基苯胺Key words
magnetism/TiO2/core-shell structure/Fe3O4@SiO2@TiO2-Au/photocatalytic reduction/p-nitroanil-ine引用本文复制引用
基金项目
陕西省自然科学基金(20210302123102)
出版年
2024
NETL
NSTL
万方数据