层级结构BiOBr的离子液体辅助合成及其对苯胺的可见光催化降解

doi:10.11944/j.issn.1000-0518.2015.09.150071

摘要/Abstract

摘要：

分别以溴代甲基咪唑反应型离子液体[C₄mim]Br、[C₈mim]Br和[C₁₂mim]Br作为溴源和软模板,通过乙二醇溶剂热处理,获得了3种不同形貌结构的溴化氧铋(BiOBr)微粉。 X射线衍射(XRD)、扫描电子显微镜(SEM)和比表面积测定的表征结果证实,产物均属四方晶系,纯度较高,且随着离子液体中阳离子取代基上碳原子数(C_n)的增多,BiOBr晶体沿着(110)晶面择优生长;微米级的BiOBr产物颗粒均是由纳米尺度的花瓣状薄片相互簇集、自组装而形成,呈球心放射状,粒径和表面孔隙均随C_n的增加而减小,但比表面积随之而增大。可见光降解苯胺的结果表明,3种BiOBr催化剂的催化活性不同,反应280 min时,降解率依次为54.13%、78.67%和95.06%;光生空穴是光降解过程的主要活性物质,羟基自由基所起的作用较小。

关键词: 离子液体, 溴化氧铋, 苯胺, 光催化, 降解

Abstract:

Three kinds of BiOBr crystal micropowders with different morphological structure have been synthesized via an ethylene glycol solvothermal route using the methylimidazolium bromide type ionic liquids [C₄mim]Br, [C₈mim]Br and [C₁₂mim]Br as bromo source and soft template. The results from X-ray diffraction(XRD), scanning electron microscopy(SEM) and Brunauer-Emmett-Teller(BET) analysis show that the as-prepared BiOBr products all belong to tetragonal phase in high purity. The BiOBr crystals along (110) lattice plane preferentially grow with the increase of carbon atom number (C_n) of substituent group in ionic liquid cation. The micro sized BiOBr particles clusters are all consisted of nanosize petal-like flakes via self-assembly, which show radial pattern from spherical center. As the C_n number increases, the particle size and surface pores all decrease, but the specific surface area increases. The three BiOBr powders possess different catalytic activity for visible photocatalytic degradation of aniline. The degradation ratios of the aniline solution are 54.13%, 78.67% and 95.06% in 280 minutes, respectively. The photogenerated holes should be the main active species in the photodegradation process, but the hydroxyl radical just plays a minor role.

Key words: ionic liquid, BiOBr, aniline, photocatalysis, degradation

张军,李晶晶,白孝康,李华博,姚海瑞,杜西刚. 层级结构BiOBr的离子液体辅助合成及其对苯胺的可见光催化降解[J]. 应用化学, 2015, 32(9): 1048-1054.

ZHANG Jun,LI Jingjing,BAI Xiaokang,LI Huabo,YAO Hairui,DU Xigang. Ionic Liquid Assisted Synthesis of Hierarchical BiOBr Crystals and Its Application in Visible Photocatalytic Degradation of Aniline[J]. Chinese Journal of Applied Chemistry, 2015, 32(9): 1048-1054.

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