溶胶-凝胶法制备ZnO纳米微球及光催化性能研究

以Zn(Ac)2·2H2O和二苷醇(DEG)为原料,采用溶胶-凝胶法,将晶核形成和生长分开,合成了由纳米晶粒聚集的类球形微球碱式醋酸锌前驱体.然后在400℃下焙烧2h得到ZnO样品.采用XRD、FT-IR、SEM、EDS和UV-vis进行表征,结果表明产物为六方纤锌矿ZnO,表面呈多孔结构.分别以ZnO纳米微球和商用ZnO纳米颗粒为光催化剂,对甲基橙进行了光催化降解研究.结果表明,溶胶-凝胶法制备的ZnO纳米微球在紫外条件下处理0.01 g·L-1的甲基橙溶液,20 min时脱色率为89％,而商用ZnO纳米颗粒处理60 min时才达到82％,前者表现出较好的光催化活性.     

低共熔溶剂条件下ZnO掺杂TiO_2微球的制备及性能

以钛酸四正丁酯(TBT)为钛源,氧化锌为掺杂物,价格便宜、可生物降解、易于合成的低共熔溶剂(氯化胆碱-尿素)为溶剂,在常温常压下合成了ZnO掺杂TiO_2微球,并在450℃下得到掺杂氧化锌的锐钛矿晶型二氧化钛。通过XRD、EDS、BET、DRS、SEM等方法对制备的样品进行表征,并研究了制备样品对活性艳蓝KN-R染料的光催化降解性能。结果表明,该方法制备的ZnO掺杂TiO_2微球的平均尺寸为40μm,比表面积为68. 95 m2/g,最可几孔径为7. 62 nm,对活性艳蓝具有明显的光催化降解能力。     

TiO_2中空微球的制备及性能

以钛酸丁酯为钛源,采用无模板溶剂热法合成了Ti O_2中空微球,并采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、N_2物理吸附-脱附(BET)对样品进行了表征和分析,以甲基橙为模拟污水考察了样品光催化降解甲基橙的能力。结果表明,Ti O_2中空微球为锐钛矿相,是由细小的纳米晶自组装形成的具有中空结构的Ti O_2微球,微球的直径为0.4~0.5μm,样品的比表面积为60 m~2/g。在8 W紫外灯照射下,将Ti O_2中空微球加到初始溶度为15 mg/L的甲基橙溶液中,在光照80 min后甲基橙降解率达到95%,表现出良好的光催化活性。     

铝掺杂纳米ZnO颗粒光催化降解活性艳蓝X-BR

以乙酸锌[Zn(CH3COO)2·2H2O]、氢氧化锂(LiOH·H2O)和氯化铝(AlCl3·6H2O)为原料,采用溶胶-凝胶法制备了纯纳米ZnO和掺铝ZnO,并用X射线衍射光谱、傅立叶红外光谱、紫外-可见吸收光谱、X射线光电子能谱和高分辨率透射电子显微镜对其进行了表征. 用紫外灯作为光源,活性艳蓝XB-R溶液为光催化反应模型降解物,研究了ZnO及掺铝ZnO的光催化性能,并考察了前驱体焙烧温度、光催化温度、光照时间、底物浓度、光催化剂的暗吸附性能、铝掺杂量以及催化剂的加入量等因素对降解率的影响. 结果表明,焙烧温度300℃时,晶粒结晶良好,粒径小;掺杂铝离子提高了ZnO的光催化活性,掺杂铝离子浓度为5%(摩尔比)的ZnO的光催化性能最好;掺杂后的样品粒度分布更均匀,且明显变小;在30℃下,加入催化剂浓度为0.1 g/L、降解时间为45 min时,对活性艳蓝XB-R溶液的降解率达到95%.     

ZnO/碳纳米管复合光催化材料对抗生素的光催化降解

采用溶胶法合成了ZnO/碳纳米管复合光催化材料,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、紫外-可见漫反射吸收光谱(UV-Vis)等手段对复合催化剂进行了表征。以氙灯(250～800 nm)为光源,盐酸四环素为降解对象,评价样品的光催化活性。比较ZnO/CNTs复合材料和纯ZnO对抗生素的降解能力,并考察光催化剂的重复利用能力。结果表明,通过溶胶法得到了在碳纳米管表面均匀、致密包覆ZnO颗粒的复合材料。由于ZnO/CNTs材料良好的吸附性能,其光催化活性高于纯ZnO,在300 W氙灯光源下反应2 h,对盐酸四环素的降解率达82.38%,同时复合材料显示了抑制ZnO光蚀的能力。     

ZnS/ZnO异质结构的制备及其光催化性能

以醋酸锌、硫脲为原料,采用简单的一步溶剂热法合成了花状Zn S微球,并分别在550、600和650℃下进行高温氧化处理,获得了Zn S/ZnO异质结构半导体材料。利用XRD、SEM、EDS、表面积分析仪、拉曼光谱仪和UV-Vis对材料的形貌、结构、比表面积和光学性质进行了测定,并以罗丹明B(Rh B)为模型污染物考察了样品的光催化性能。结果表明:原位合成的样品为立方相Zn S微球,经过550℃高温氧化1 h后,由于O原子的进入,生成少量ZnO,经过600℃高温氧化1 h后形成了Ⅱ型异质结构Zn S/ZnO,经过650℃高温氧化1 h后,样品基本上成为ZnO。随着高温氧化温度的升高,样品的禁带宽度整体呈下降趋势。光催化结果显示:Zn S/ZnO异质结构具备较优的光催化性能,紫外光照射40 min,Rh B降解率达到98.5%。     

TiO2中空微球的制备及性能研究

以钛酸丁酯为钛源,采用无模板法溶剂热合成了中空TiO2微球,并采用了X射线衍射(XRD)、扫描电镜(SEM)、透射电镜（TEM）、N2物理吸附-脱附（BET）等手段对样品进行了表征和分析,以甲基橙为模拟污水研究了样品光催化降解甲基橙的能力。结果表明, 中空TiO2微球为锐钛矿相,是由细小的纳米晶自组装组成的具有中空结构的TiO2微球,微球的直径为0.4~0.5 μm。样品具有介孔结构和较高的比表面积,在紫外光照射下,加入中空TiO2微球到初始溶度为15 mg/L的甲基橙溶液中,在光照80 min后降解甲基橙达到了95%,表现出良好的光催化活性。     

花状微球结构MoS2的制备及其光催化性能研究

采用简单的水热溶剂法,以钼酸钠(Na2MoO4·2H2O)为钼源,硫脲(CS(NH2)2)为硫源,通过调控反应温度、反应时间等合成工艺参数,成功制备了花状微球结构的二硫化钼(MoS2)粉末.采用X射线衍射仪(XRD)、扫描电镜(SEM)等对MoS2粉末的结构和形貌进行了表征.结果表明:当反应温度为220℃,反应时间为24 h,反应环境pH=1时,可制备出花状微球结构的MoS2粉末.通过分析MoS2粉末对罗丹明B的光催化降解率研究其光催化性能,对罗丹明B的降解率达到93.83％,是一种理想的光催化材料.     

Zr–Al共掺对ZnO光催化剂结构和催化性能的影响

利用水热处理结合焙烧的方法分别制备了Zr、Al掺杂及Zr–Al共掺的ZnO光催化剂。研究了制备的光催化剂样品的相结构和光谱性能;以紫外光(λ=254nm)为光源,酸性橙Ⅱ为降解对象,进行光催化活性测试;考察了Zr、Al掺杂对ZnO光催化剂反应活性的影响。研究表明,制备的产物均为六方晶系纤锌矿结构的ZnO;Zr、Al掺杂及Zr–Al共掺的ZnO样品的光催化活性相对于纯ZnO均有较大程度的提高,而且Zr–Al共掺的ZnO的光催化性能明显优于单一掺杂的。Zr–Al共掺可以明显改善ZnO表面状态,使ZnO具有更丰富的表面羟基,同时可以抑制光生电子–空穴对的复合,从而有利于光催化活性和稳定性的提高。     

微波辅助纳米Cu(OH)_2/ZnO复合材料的合成与光催化研究

以乙酸锌、氢氧化锂、氯化铜为原料,采用微波辅助加热溶胶-凝胶法制备了不同尺寸的ZnO和Cu(OH)2/ZnO复合型光催化剂,并用XRD、UV-Vis、HR-TEM、IR和SAED对其进行了表征。采用15 W的紫外灯和室外可见光作为光源,活性艳蓝X-BR为光催化反应模型污染物,研究了在各种不同制备条件下ZnO以及Cu(OH)2/ZnO的光催化性能。实验结果表明,在温度50℃下反应10 min,所合成的ZnO粒径最小,为2.59 nm,蓝移现象最明显,说明其光催化活性最佳。在紫外光下,对浓度为40 mg?L?1的活性艳蓝X-BR溶液进行光催化降解,当降解时间为100 min时,光降解率可达到78%。所制备的Cu(OH)2/ZnO(铜锌质量比3:7)复合材料其分散性最好,团聚现象最小。对浓度为40 mg?L?1的活性艳蓝X-BR溶液进行光化学降解,当降解温度为120℃时,光降解率可达到84%。     

Self-assembly synthesis of ZnO with adjustable morphologies and their photocatalytic performance

ZnO with hierarchical microspheres and hexagonal prisms structures were successfully synthesized by hydrothermal microemulsion route. Based on X-ray diffraction and scanning electron microscopy observation of the products at the different reaction time periods, the formation mechanism of three-dimensional hierarchical ZnO microspheres was proposed. Ultraviolet and visible diffuse reflectance spectra indicated that as-synthesized ZnO microspheres had enhanced absorption in both ultraviolet and visible light areas. The photocatalytic activities of as-synthesized products were evaluated by monitoring the degradation of methylene blue solution. Due to the synergistic effects of the high crystallization and special hierarchical structure, the hierarchical ZnO microsphere exhibited the highest photocatalytic activity.     

Attachment of ZnO nanoparticles onto layered double hydroxides microspheres for high performance photocatalysis

In this study, ZnO nanoparticles were successfully deposited on the surface of ZnMgAl–CO₃–LDHs microspheres to form ZnO/ZnMgAl–CO₃–LDHs heterojunction photocatalysts by coprecipitation process. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy. The results show that ZnO nanoparticles with diameters about 10–80 nm are tightly grown on the nanosheets of the ZnMgAl–CO₃–LDHs microspheres. Compared with the pristine ZnMgAl–CO₃–LDHs microspheres and pure ZnO, the photocatalytic activity of the heterojunction ZnO/ZnMgAl–CO₃–LDHs photocatalyst is significantly enhanced towards the degradation of phenol under UV light irradiation. The enhancement of the photocatalytic activity of the heterojunction catalysts can be ascribed to their improved light absorption property and the lower recombination rate of the photoexcited electrons and holes during the photocatalytic reaction. The optimal molar ratio of ZnO/ZnMgAl–CO₃–LDHs for the photocatalysis is 3. The heterojunction photocatalyst ZnO/ZnMgAl–CO₃–LDHs may be a promising photocatalyst for future application in water treatment due to its excellent performance in degradation of phenol.     

微波均相沉淀法制备纳米ZnO及其光催化性能

以硫酸锌和尿素为原料,采用微波均相沉淀法制备出了纳米ZnO. 探讨了反应物配比、反应物浓度、反应时间、反应温度等条件对产物的影响. 并用TEM, IR, TGA, XRD, UV-Vis等测试手段对其进行了表征. 利用紫外-可见分光光度计测试了光吸收特性,发现纳米ZnO对200~380 nm波长范围的光有很强的吸收性,在可见光范围内也有较强的吸收. 研究了纳米ZnO光催化降解甲基橙的动力学行为,在紫外光直接照射下,光催化降解甲基橙,以分光光度法测量甲基橙的即时浓度,从而得出了不同条件下甲基橙降解的脱色速率,以比较不同的降解效果.     

离子液体水热法辅助合成稀土Ce掺杂ZnO纳米材料的制备及其应用研究

以1-甲基咪唑和氯代正丁烷为原料,合成1-丁基-3-甲基咪唑氯盐离子液体;以醋酸锌[Zn(Ac)2]、硫酸锌(ZnSO4)和氯化锌(ZnCl2)为锌源,在1-丁基-3-甲基咪唑氯盐离子液体和丙氨酸体系中与硝酸铈反应,经水热合成法制备得到Ce掺杂的纳米ZnO。采用扫描电子显微镜(SEM)、紫外-可见光吸收光谱(UV-Vis)、X射线衍射仪(XRD)、X射线光电子能谱分析(XPS)和红外光谱(FT-IR)对产品进行表征。以亚甲基蓝(MB)为目标降解物,采用UV-Vis检测,考察了Ce掺杂的纳米ZnO的光催化活性。研究表明,焙烧温度对光催化的晶体结构和光催化活性产生较大的影响;2%Ce/ZnO、焙烧温度为500℃、催化时间为30 min、亚甲基蓝用量0.05 g、pH值为10时降解率可达99.5%以上。     

Preparation of rare earth-doped ZnO hierarchical micro/nanospheres and their enhanced photocatalytic activity under visible light irradiation

Rare earth-doped ZnO hierarchical micro/nanospheres were prepared by a facile chemical precipitation method and characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV-visible diffuse reflectance spectroscopy and photoluminescence spectroscopy. The results showed that the as-synthesized products were well-crystalline and accumulated by large amount of interleaving nanosheets. It was also observed that the rare earth doping increased the visible light absorption ability of the catalysts and red shift for rare earth-doped ZnO products appeared when compared to pure ZnO. The photocatalytic studies revealed that all the rare earth-doped ZnO products exhibited excellent photocatalytic degradation of phenol compared with the pure ZnO and commercial TiO₂ under visible light irradiation. Nd-doped ZnO had the highest photocatalytic activity among all of the rare earth-doped ZnO products studied. The optimal Nd content was 2.0 at% under visible light irradiation. The enhanced photocatalytic performance of rare earth-doped ZnO products can be attributed to the increase in the rate of separation of photogenerated electron–hole pairs and hydroxyl radicals generation ability as evidenced by photoluminescence spectra.     

YBO3微米球的水热合成及光催化性能

采用水热法制备了YBO3微米球。利用XRD、FESEM、TEM、XPS和UV-Vis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，采用CHI660E电化学系统研究了样品的电化学性能，并通过罗丹明B的降解反应考察了样品的光催化活性。结果表明：YBO3微米球由纳米片自组装形成；与YBO3微米颗粒相比，YBO3微米球的吸收光谱发生明显红移，在紫外光范围内有较强的吸收；并且YBO3微米球具有较高的光电流和较小的载流子迁移阻力，光催化活性明显提高，40 min对罗丹明B的降解率达到90.9%。     

YBO3微米球的水热合成及光催化性能

采用水热法制备了YBO_3微米球。利用XRD、FESEM、TEM、XPS和UV-Vis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,采用CHI660E电化学系统研究了样品的电化学性能,并通过罗丹明B的降解反应考察了样品的光催化活性。结果表明:YBO_3微米球由纳米片自组装形成;与YBO_3微米颗粒相比,YBO_3微米球的吸收光谱发生明显红移,在紫外光范围内有较强的吸收;并且YBO_3微米球具有较高的光电流和较小的载流子迁移阻力,光催化活性明显提高,40 min对罗丹明B的降解率达到90.9%。     

Synthesis of multi-shelled ZnO hollow microspheres and their improved photocatalytic activity

Herein, we report an effective, facile, and low-cost route for preparing ZnO hollow microspheres with a controlled number of shells composed of small ZnO nanoparticles. The formation mechanism of multiple-shelled structures was investigated in detail. The number of shells is manipulated by using different diameters of carbonaceous microspheres. The products were characterized by X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. The as-prepared ZnO hollow microspheres and ZnO nanoparticles were then used to study the degradation of methyl orange (MO) dye under ultraviolet (UV) light irradiation, and the triple-shelled ZnO hollow microspheres exhibit the best photocatalytic activity. This work is helpful to develop ZnO-based photocatalysts with high photocatalytic performance in addressing environmental protection issues, and it is also anticipated to other multiple-shelled metal oxide hollow microsphere structures.     

Ag/AgBr/BiOBr hollow hierarchical microspheres with enhanced activity and stability for RhB degradation under visible light irradiation

Ag/AgBr/BiOBr hollow hierarchical microspheres were synthesized through a one-pot solvothermal process. The phase structure, morphology and optical property of the samples were characterized by XRD, SEM, XPS and DRS. Ag/AgBr/BiOBr hollow microspheres exhibited higher photocatalytic activity and improved stability than AgBr/BiOBr nanoplates for rhodamine B degradation under visible light irradiation. The enhanced activities of Ag/AgBr/BiOBr could be attributed to the hollow structure and Ag deposition, which is favorable for adsorption of reactants, enhancement of photoadsorption and transfer of photogenerated carriers. Ag deposition also prevented the decomposition of AgBr under light illumination and contributed to an improved stability.