郭梦圆,张雪乔,罗坤,郭旭晶,孟勇.焙烧温度对ZnSn水滑石结构及光催化性能的影响[J].环境科学学报,2021,41(2):504-511
焙烧温度对ZnSn水滑石结构及光催化性能的影响
- Effect of calcination temperature on structure and photocatalytic properties over ZnSn-LDHs
- 基金项目：成都市科技局技术研发创新项目（No.2019-YF05-01838-SN）；四川省大学生创新创业项目（No.S202010621116）；四川省环境治理与生态保护重大科技专项（No.2018SZDZX0024）
- 孟勇
- 上海欧尼仪器科技有限公司, 上海 201619
- 摘要：采用共沉淀和热处理法合成了一系列ZnSn-LDHs/MMO光催化剂，利用X射线衍射（XRD）、N2吸附-脱附、傅里叶变换红外（FTIR）、紫外漫反射（UV-Vis-DRS）、光致发光光谱（PL）和电化学阻抗（EIS）等技术对其进行表征，并以甲基橙（MO）为降解物，考察其光催化性能.结果表明，ZnSn-LDHs在焙烧温度为200℃时，羟基和CO32-开始脱除，600℃时主要产物为ZnO和SnO2的复合氧化物，800℃时形成Zn2SnO4的尖晶石结构.热处理步骤可通过结构重组改善催化剂的织构性能，保留其表面部分羟基，降低其禁带宽度，延长电子空穴对寿命.其中，600℃焙烧生成的ZnSn-MMO-600具有最佳的光催化性能，在pH为7、催化剂投加量为2 g·L-1、紫外光照为90 min条件下，MO的降解率在95%以上，反应符合一级动力学模型，5次循环后，MO的降解率仍近90%.光催化反应中·OH是主要的氧化性自由基.
- Abstract：Layered double hydroxides containing zinc and stannum (ZnSn-LDHs) and the mixed metal oxides (ZnSn-MMO) were prepared through co-precipitation and calcination method. The as-prepared samples were characterized by X ray diffraction (XRD), N2 absorption-desorption, Fourier-transform infrared (FT-IR), UV-Vis diffuse reflectance spectra (DRS), photoluminescence spectroscopy (PL) and electrochemical impedance spectra (EIS). Under the irradiation of ultraviolet light, the photocatalytic properties of various samples were investigated by using methyl orange (MO) degradation as the probe reaction. The results showed that the hydroxyl group and CO32- of ZnSn-LDHs begin to be extracted when the calcination temperatre was over 200 ℃, then the ZnO-SnO2 compound oxide formed at 600 ℃. The Zn2SnO4 of spinel structure was mainly formed as the temperature reached to 800 ℃. The process of calcination can dramatically promote surface property, reduce energy band width, enhance the separation efficiency of photo-induced carriers and surface hydroxyl content. The photocatalytic activities of ZnSn-MMO with calcination temperature at 600 ℃ presents the best efficiency for MO photodegradation. And the degradation rate of MO is more than 95% after 90 min of UV irradiation under the initial pH=7 and the catalyst dosage of 2 g·L-1. The first-order kinetic degradation rate constant of SA over ZnSn-MMO-600 is 3.2 times higher than that of ZnSn-LDHs. The degradation rate of MO was still nearly 90% after five cycles, with the major radicals ·OH.
