微波辐射对纳米ZnO材料物理性质与光催化活性的影响

在采用沉淀法制备ZnO的过程中, 用不同功率(100, 150, 200, 250和300 W)的微波辐射ZnO前驱体, 获得了一系列纳米ZnO材料, 并对合成材料的晶型结构、 形貌及表面物理化学性质进行了表征. 结果表明, 与普通沉淀法制备的ZnO相比, 使用微波辐射后ZnO半导体材料的晶型仍为六方纤锌矿结构, 但吸收光谱发生了蓝移或红移, 且比表面积均有不同程度的增加. 同时, 微波辐射功率不同, ZnO形貌差异明显, 并随着微波功率变化分别呈现纳米颗粒、 椭圆形纳米团簇、 纳米片和球状纳米簇等多样化形态. 以罗丹明B为模型分子, 分别在紫外及微波辅助光催化条件下考察了所合成纳米ZnO材料的光催化性能. 结果显示, 经不同功率微波辐射作用后, ZnO的光催化活性均得到了不同程度的提高, 并且明显高于市售P25和未经微波辐射作用的ZnO.     

纳米Ag/ZnO微波辅助合成与微波增强光催化罗丹明B

本文通过微波辅助、程序升温溶剂热以及煅烧等不同方法制备了系列纳米复合材料Ag/ZnO,并采用X-射线衍射(XRD)、紫外-可见漫反射吸收光谱(UV-Vis/DRS)、X射线光电子能谱(XPS)、氮气吸附-脱附测定以及扫描电子显微镜配合X-射线能量色散谱仪(SEM-EDS)等测试手段对上述合成材料的晶型结构、形貌及表面物理化学性质进行了表征。结果表明,合成过程中辅以微波后其纤锌矿晶型结构未发生明显变化。但同时,其光的吸收性质以及粒子尺寸、形貌以及颗粒分布等方面则有较大改变。其中,经微波辐射、程序升温溶剂热以及煅烧三步处理的样品(mcd-Ag/ZnO)更多呈现规则的六棱柱结构。在紫外光照射和微波辐射下,合成产物光催化降解罗丹明B的实验结果显示,经微波辅助合成的Ag/ZnO光催化活性较未经微波处理样品的活性有较大提高,且明显高于市售P25。同时,mcd-Ag/ZnO在微波辐射下的光催化活性也被有效增强。     

微波辅助合成纳米复合材料Ag/ZnO-ZnS及其光催化降解若丹明B初步研究

采用微波辅助合成方法制备了具有高光催化活性的纳米复合材料Ag/ZnO-ZnS,经X-射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜配合X-射线能量色散谱仪(SEM-EDS)以及氮气吸附-脱附测定等对合成材料的结构、形貌和表面物理化学性质进行了表征。结果表明,经微波处理后的纳米复合材料Ag/ZnO-ZnS中Ag以单质形式存在,具有纤锌矿晶型结构,属介孔材料,平均孔径约为4.1nm,比表面积更大,颗粒分布更加均匀。通过模型分子若丹明B分别考察了紫外和微波辐射下Ag/ZnO-ZnS的光催化活性,结果显示,微波辅助合成的Ag/ZnO-ZnS具有更高的光催化活性,其在微波增强光催化条件下,40min内对若丹明B脱色率达99%以上,明显高于市售P25等其他体系。     

纳米复合材料Ag/TiO_2-ZrO_2的制备及其微波增强光催化降解甲基橙

采用EO20PO70EO20(P123)作模板剂,通过溶胶-凝胶-程序升温溶剂热一步法,并经萃取处理制备了具有光催化活性的纳米复合材料Ag/TiO2-ZrO2.用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、N2吸附-脱附测定和扫描电子显微镜配合X射线能量色谱仪(SEM-EDS)等测试手段对其组成、结构及形貌等进行了表征.结果表明,复合材料Ag/TiO2-ZrO2中Ag以单质形式存在,材料具有双孔结构,颗粒分布较均匀,结构也较规整,平均孔径约为3.6和9.0nm.通过微波增强光催化降解染料甲基橙的实验,对复合材料Ag/TiO2-ZrO2的光催化活性进行了探究.实验结果表明,微波辅助光催化效果优于紫外辐射,并且萃取后的合成产物Ag/TiO2-ZrO2在90min内对甲基橙的降解率可达81.5%,其活性高于市售P25以及TiO2-ZrO2.     

圆形片状纳米复合材料Ag/ZnO-ZrO2微波辅助合成与多模式光催化罗丹明B

采用微波辅助结合沉淀法制备了以ZnO为主体的纳米复合材料Ag/ZnO-ZrO₂。通过X射线粉末衍射(XRD)、紫外-可见漫反射吸收光谱(UV-Vis/DRS)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和N2吸附-脱附等表征手段研究了微波辐射对Ag/ZnO-ZrO₂晶型结构、形貌及表面物理化学性质的影响。结果表明, 在200 W微波辐射作用下, 该样品晶型结构未发生明显变化, 但Ag的衍射峰明显增强, 同时, 其晶粒尺寸、光吸收性质和表面物理化学性质等方面则发生改变, 尤其是样品Ag/ZnO-ZrO₂的形貌呈现了圆形片状结构。分别在紫外和微波辅助条件下对纳米复合材料的光催化性能进行了一系列考察, 同时为了进一步评价所合成样品在太阳光作用下的实用价值, 又考察了Ag/ZnO-ZrO₂在模拟日光条件下的光催化性能。结果显示, 紫外光作用下, 纳米复合材料Ag/ZnO-ZrO₂的光催化活性高于市售P25以及未经微波处理的样品, 且在微波辅助光催化条件下, 其活性有较大程度提高。200 W微波功率下所合成样品Ag/ZnO-ZrO₂在模拟日光作用下显现出较高活性。另外, 根据紫外光条件下对光催化活性物种的捕获实验提出了Ag/ZnO-ZrO₂可能的光催化机理。     

圆形片状纳米复合材料Ag/ZnO-ZrO2微波辅助合成与多模式光催化罗丹明B

采用微波辅助结合沉淀法制备了以Zn O为主体的纳米复合材料Ag/Zn O-Zr O_2。通过X射线粉末衍射(XRD)、紫外-可见漫反射吸收光谱(UV-Vis/DRS)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和N2吸附-脱附等表征手段研究了微波辐射对Ag/Zn O-Zr O_2晶型结构、形貌及表面物理化学性质的影响。结果表明,在200 W微波辐射作用下,该样品晶型结构未发生明显变化,但Ag的衍射峰明显增强,同时,其晶粒尺寸、光吸收性质和表面物理化学性质等方面则发生改变,尤其是样品Ag/Zn O-Zr O_2的形貌呈现了圆形片状结构。分别在紫外和微波辅助条件下对纳米复合材料的光催化性能进行了一系列考察,同时为了进一步评价所合成样品在太阳光作用下的实用价值,又考察了Ag/Zn O-Zr O_2在模拟日光条件下的光催化性能。结果显示,紫外光作用下,纳米复合材料Ag/Zn O-Zr O_2的光催化活性高于市售P25以及未经微波处理的样品,且在微波辅助光催化条件下,其活性有较大程度提高。200 W微波功率下所合成样品Ag/Zn O-Zr O_2在模拟日光作用下显现出较高活性。另外,根据紫外光条件下对光催化活性物种的捕获实验提出了Ag/Zn O-Zr O_2可能的光催化机理。     

花球状异质结构复合材料ZnS/ZnO/ZnWO4多模式光降解与光解水制氢

通过微波辅助水热两步法制备了复合材料ZnS/ZnO/ZnWO_4,并采用X射线衍射(XRD)、紫外-可见漫反射吸收光谱(UVVis DRS)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)以及N_2吸附-脱附等测试手段对其晶相结构、组成、形貌、表面物理化学性质及光吸收性能等进行了表征。结果显示,该复合材料呈现大小均匀的花球状结构,其花球是由立方晶相ZnS纳米颗粒、六方晶相ZnO与单斜晶相ZnWO_4纳米棒构成。微波的极化作用导致复合材料ZnO/ZnWO_4的晶粒尺寸、比表面积和孔体积较单体ZnWO_4明显变大。再次微波辐射复合ZnS后,复合材料ZnS/ZnO/ZnWO_4的晶粒尺寸进一步变大,同时二次微波作用导致其比表面积和孔体积由于花球内部的紧致而变小,但复合材料依旧保持花球状结构。以孔雀石绿为目标降解物,研究了花球状ZnS/ZnO/ZnWO_4增强的多模式光催化降解性能。而光解水制氢实验结果表明,ZnS/ZnO/ZnWO_4复合材料具有优异的产氢能力(376.9μmol·h~(-1)·g~(-1)),是市售P25的246.5倍,其增强的光解水制氢性能与复合材料优异的花球形貌、三元异质结构以及光催化反应中的多途径电子传递有关。     

CTAB作用下纳米复合材料ZnO-TiO2制备与多模式光催化降解罗丹明B

在模板剂十六烷基三甲基溴化铵作用下,通过溶胶-凝胶与程序升温溶剂热法制备了纳米复合材料ZnOTiO2(CTAB).经X-射线衍射(XRD)、紫外-可见漫反射吸收光谱(UV-Vis/DRS)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和N2吸附-脱附测试等手段对其组成、结构和形貌等进行了表征.结果显示,合成产物ZnO-TiO2(CTAB)主要晶型为ZnO纤锌矿,并部分生成ZnTiO3.同时,该合成产物经CTAB作用后,其对光的吸收发生明显红移,且平均孔径明显变小,BET值增大.在紫外光、可见光、模拟日光和微波辅助等不同模式光催化降解罗丹明B的实验研究中,与未经CTAB作用的样品ZnO-TiO2相比,ZnO-TiO2(CTAB)具有更高的光催化性能.同时,该复合材料在紫外光条件下,对甲基橙、罗丹明B、结晶紫、亚甲基蓝和龙胆紫5种不同结构染料的光催化中均表现出良好的降解效果.     

微波诱导燃烧法合成类花状ZnO纳米材料及其晶体结构、荧光性质研究

以硝酸锌[Zn(NO3)2.6H2O]和尿素[CO(NH2)2]作前驱体,通过微波诱导燃烧技术可控合成具有不同形貌的ZnO纳米晶体,并用热重分析和差热分析进行了研究。对各种生长条件:微波功率,辐射时间和尿素/Zn2+物质的量的比对ZnO纳米晶体形貌的影响作了分析。结果表明:尿素/Zn2+物质的量的比对ZnO纳米材料的形貌具有显著影响。X衍射图表明合成的ZnO纳米结构呈六角形。傅里叶变换红外光谱图中400~500 cm-1处明显的峰为Zn-O的振动峰。ZnO纳米结构的发光光谱在366 nm的带边发射,因缺陷又由许多可见光发射峰组成。用扫描电子显微镜、透射电子显微镜、选区电子衍射研究了花状ZnO纳米结构的增长机理。本方法仅需几分钟就获得的了ZnO纳米结构。     

低共熔溶剂辅助水热法合成分层球状微/纳米ZnO晶体及其光催化性能

使用尿素-氯化胆碱低共熔溶剂(UCC-DES),采用水热合成和反溶剂(乙醇)法,以化工材质ZnO粉末为原料制备了分层的球状微/纳米ZnO晶体.分析了反应时间、反溶剂的种类和含量对ZnO晶体形貌的影响以及ZnO晶体析出的原因.并将制备的分层球状ZnO微/纳米晶体应用于光催化降解甲基橙.结果表明,制备的ZnO晶体对甲基橙有良好的光催化降解性能.     

ZnO/Ag微米球的合成与光催化性能

用微波辅助多元醇法对预先制备的ZnO微米球进行修饰,合成了载银氧化锌微米球（ZnO/Ag）. 利用X射线衍射仪、场发射扫描电子显微镜、透射电子显微镜、X射线光电子能谱仪、紫外-可见双光束分光光度计和光致发光光谱仪等对样品的结构、形貌和光学性能进行了表征. 在紫外光照射下,通过亚甲基蓝的降解反应研究了样品的光催化活性. 结果表明,所制备的ZnO/Ag微米球是由面心立方的Ag纳米颗粒附着在纤锌矿结构的ZnO球表面形成;与ZnO相比,ZnO/Ag的紫外-可见光吸收光谱发生明显红移,在紫外和可见光范围均有较强的吸收;随着Ag含量的增加,ZnO/Ag荧光光谱强度先减弱后增强;与ZnO相比,ZnO/Ag的光催化活性明显提高,AgNO₃ 浓度为0.05 mol/L时制得的ZnO/Ag光催化活性最高.     

Sunlight responsive photocatalysts: AgBr/ZnO hybrid nanomaterial

A novel high-effective sunlight-induced AgBr/ZnO hybrid nanophotocatalyst has been synthesized and it was characterized by different techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and ultraviolet-visible spectrophotometry (UV-vis). The AgBr/ZnO hybrid nanophotocatalyst has excellent photocatalytic activity for photodegradation of methyl orange (MO) under sunlight irradiation. The MO degradation efficiency for AgBr/ZnO is about 98% after 1 hour under sunlight irradiation. These results suggested that AgBr/ZnO is a promising candidate for the development of highly efficient sunlight photocatalysts. In addition, the photocatalytic mechanism of AgBr/ZnO under sunlight irradiation is illustrated and discussed.     

Microwave-assisted solution synthesis and photocatalytic activity of Ag nanoparticles supported on ZnO nanostructure flowers

Ag nanoparticles supported on the surface of three-dimensional (3D) flower-like ZnO nanostructure were synthesized by a microwave-assisted solution method. The obtained products were characterized by X-ray diffraction analysis, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectrophotometry, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The analytical results confirmed homogeneously distributed Ag nanoparticles supported on the surface of flower-like ZnO nanostructure. The photocatalytic effect of the heterostructure Ag/ZnO nanocomposites was investigated using photodegradation under ultraviolet (UV) light of methylene blue as model dye. The heterostructure Ag/ZnO nanocomposites exhibited much higher photocatalytic activity than pure ZnO flowers. The improved photocatalytic properties are attributed to formation of a Schottky barrier at the metal–semiconductor interface of the Ag/ZnO nanocomposites.     

Time growing comparison for ZnO nanorod by using microwave irradiation method

In this study, zinc oxide (ZnO) nanorod were successfully prepared at different growth times (15, 30 and 60 min) using the microwave irradiation method. The ZnO nanorods were simply synthesized at a low temperature (90 °C) with low power microwave assisted heating (about 100 W) and a subsequent ageing process. The synthesized nanorod were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and Ultraviolet–Visible spectroscopy (UV–Vis). The FESEM images showed nanorods with diameter ranging between 50 and 150 nm, and length of 150–550 nm. The XRD results indicate that ZnO nanorods of different time of growth exhibits pure wurtzite structure with lattice parameters of 3.2568 and 5.2125 Å. UV–Vis characterization showed that energy gap decreases with increase in time. The result also shows that growth of ZnO at 60 min produces an energy band gap of 3.15 eV. In general, the results of the study confirm that the microwave irradiation method is a promising low temperature, cheap and fast method for the production of ZnO nanostructures.     

Microwave-assisted synthesis of ZnO and its photocatalytic activity in degradation of CTAB

Nanosized zinc oxide (nano-ZnO) was prepared by a microwave irradiation method using zinc nitrate and triethanolamine as starting materials and distilled water as a solvent. The as-prepared powder was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic degradation of cetyltrimethylammonium bromide (CTAB) using the prepared material under UV irradiation was studied.The effects of ZnO dosage and initial pH on the photodegradation of CTAB were investigated. As the ZnO load increased, the CTAB degradation first increased and then decreased. The optimum ZnO dosage was 3 g L^–1. Photodegradation of CTAB is more efficient in slightly alkaline media (pH 9).     

Large-scale synthesis of ZnO balls made of fluffy thin nanosheets by simple solution process: structural, optical and photocatalytic properties

This paper reports a large-scale synthesis of ZnO balls made of fluffy thin ZnO nanosheets by simple solution process at low-temperature of 65±2°C. The synthesized ZnO structures were characterized in detail in terms of their morphological, structural, optical and photocatalytic properties. The detailed morphological characterizations, done by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), confirmed that the synthesized products are ZnO balls which are made by accumulation of hundreds of thin ZnO nanosheets. Interestingly, it is seen that the nanosheets are arranged in such a special fashion that they made ball-like morphologies. Detailed structural examinations revealed that of as-synthesized ZnO products are well-crystalline and possessing wurtzite hexagonal phase. The optical property, measured by UV-Visible spectroscopy, substantiated good optical properties for as-synthesized ZnO balls. The as-synthesized ZnO balls were utilized as an efficient photocatalysts for the photocatalytic degradation of methylene blue (MB) dye. Almost complete degradation of MB was observed in presence of ZnO balls composed of nanosheets within 70 min under UV-light irradiation. By comparing the photocatalytic performance with commercially available TiO(2)-UV-100, it was observed that the synthesized ZnO balls exhibited superior photocatalytic performance as compared to TiO(2)-UV-100 photocatalyst.