Insight into the photocatalytic activity of ZnCr-CO3 LDH and derived mixed oxides
Insight into the photocatalytic activity of ZnCr-CO3 LDH and derived mixed oxides
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DOI：
10.1016/j.apcatb.2015.01.029
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发表时间：
2015-07-01
影响因子：
22.1
通讯作者：
Prevot, Vanessa
中科院分区：
文献类型：
--
作者：
Pausova, Sarka;Krysa, Josef;Prevot, Vanessa
采用直接共沉淀法和阴离子交换法两步合成了ZnCr-CO 3层状双氢氧化物（LDH）。为了研究热处理对ZnCr-CO 3 LDH光催化活性的影响，采用原位热X射线衍射和热分析（TGA/DTA）研究了基质的热分解过程。通过X射线衍射、红外光谱、紫外-可见漫反射光谱、氮吸附、扫描和透射电子显微镜等技术对不同热处理条件下所得材料的结构和织构性质进行了表征。在研究橙子II（OII）光降解之前，研究了未煅烧和煅烧的ZnCr-CO 3 LDH对油的吸附行为，证明LDH热分解导致吸附行为的净减少。所有样品均诱导OII的光降解。煅烧后得到的化合物在600摄氏度以上显示出最高的光催化活性，这归因于形成结晶良好的ZnO和ZnCr 2 O 4尖晶石，导致OIL的完全矿化。最佳光催化条件被定义为0.5 g L-1的光催化剂和碱性pH条件。为了进一步突出氧化过程，进行了实验与4-氯苯酚，这是不吸附在LDH表面和异丙醇和对苯二甲酸，用作HO中心点自由基陷阱。在光催化降解机理方面，既有羟基自由基的产生，也有与光催化剂表面空穴的直接作用。(C)2015 Elsevier B. V.版权所有。
ZnCr-CO3 layered double hydroxide (LDH) has been prepared by a two-step process combining direct coprecipitation and anionic exchange. To investigate the influence of thermal treatment on ZnCr-CO3 LDH photocatalytic activity, the thermal decomposition of the matrix was studied by in-situ thermal X-ray diffraction and thermal analysis (TGA/DTA). The structure and the textural properties of the materials obtained upon different thermal treatment have been characterized by several techniques such as Xray diffraction, FTIR, UV-vis diffuse reflectance spectroscopy, N-2 adsorption, scanning and transmission electronic microscopy. Prior to study Orange II (OII) photodegradation, adsorption behavior of uncalcined and calcined ZnCr-CO3 LDH toward Oil was studied evidencing that LDH thermal decomposition leads to a net decrease of the adsorption behavior. All the samples induce the photodegradation of OII. The compounds obtained after calcination above 600 degrees C display the highest photocatalytic activity attributed to the formation of well crystallized ZnO and ZnCr2O4 spinel leading to complete mineralization of OIL Optimal photocatalytic conditions were defined as 0.5 g L-1 of photocatalyst and basic pH conditions. To further highlight the oxidation process, experiments with 4-chlorophenol, which is not adsorbed on LDH surface and with isopropanol and terephthalic acid, used as HO center dot radical trap, were carried out. In terms of photodegradation mechanism, both hydroxyl radical generation in bulk and direct interaction with hole on the surface of the photocatalysts were evidenced. (C) 2015 Elsevier B.V. All rights reserved.