三维花状氧化锌纳米材料的合成及其光催化性能

采用水热法,以硝酸锌[Zn(NO3)2.6H2O]和氨水(NH3.H2O)为原料制备了三维花状氧化锌纳米材料。采用X射线衍射(XRD)、扫描电镜(SEM)等测试方法研究了样品的成分、形貌和结构。研究结果显示:样品为六方纤锌矿结构的花状ZnO纳米材料。为了评估氧化锌纳米材料的光催化性能,进行了氧化锌纳米材料对有机染料甲基橙的光催化降解实验。实验结果表明,氧化锌纳米结构对甲基橙的光催化降解具有较好的催化作用,催化活性与氧化锌纳米结构的特殊形貌有关系。     

氧和氩等离子辅助电子束蒸发制备高质量ZnO薄膜

采用等离子辅助电子束蒸发技术制备高纯金属锌膜，然后在氧气气氛下经高温热处理得到氧化锌的多晶薄膜。X射线衍射谱的结果表明：未经热氧化样品由金属锌和氧化锌纳米晶组成，随着热氧化温度的升高氧化锌纳米晶粒长大，形成纳米氧化锌多晶薄膜且薄膜结晶性增强；光致发光谱表明：样品均具有较强的紫外自由激子发光。由于未经热氧化样品中氧化锌纳米晶粒较小，具有较强的量子限域效应，因而经高温氧化后样品发光峰有较大红移。随着热氧化温度的进一步升高，束缚激子发射随热氧化温度升高而减弱，且发光峰位随热氧化温度升高出现蓝移；变温光致发光谱表明：紫外发光主要来自自由激子发射。     

离子液体辅助水热法制备锡酸锌的研究

采用离子液体辅助水热法制备锡酸锌,考察了溶液pH值、水热反应时间及水热反应温度对锡酸锌晶体结构、形貌及光催化性能的影响。采用X射线衍射(XRD)确定锡酸锌的晶体结构、结晶水平及相的纯净程度;透射电子显微镜(TEM)用来分析制得的锡酸锌的形貌;通过在紫外光照射下光催化降解亚甲基蓝进行锡酸锌的光催化性能研究,结果表明:溶液pH值为9、水热反应温度为220℃、水热反应时间为32h制得的锡酸锌对亚甲基蓝有最高的光催化降解活性。对锡酸锌降解亚甲基蓝的光催化机理探究表明:锡酸锌光催化活性的差异主要归因于缺陷,缺陷往往成为电子-空穴复合中心,导致光催化活性不高;羟基自由基是光催化反应的主要活性物种。     

分光光度法研究PbSnO3纳米粒子对甲基橙溶液的光降解性

采用共沉淀法制备出完整的立方相锡酸铅纳米粒子,并研究了其对甲基橙溶液的光催化降解性能.结果表明：PbSnO3催化剂对甲基橙溶液有良好的光催化降解效果.当催化剂用量为60mg/L,反应时间为80min时,降解率可达90％以上.     

强悬浮性纳米TiO2的制备、表征及光催化活性研究Ⅱ.光催化活性研究

将甲基橙溶液作为模拟废水,在紫外灯照射下,通过测量甲基橙溶液在470nm处吸光度的变化,考察了热分解制备纳米TiO2后处理过程中采用硅油淬火改性和自然冷却所得产物的光催化活性,并初步分析了两者光催化甲基橙的机理和在35min内的降解率和动力学反应过程。结果表明：两者均具有良好的光催化降解效果,且活性差别不大。但经硅油淬火改性的纳米TiO2因在水中具有强悬浮性,可更为有效地利用外部光源在工业废水的表层降解有害成分。     

溶胶-凝胶法制备纳米氧化锌及其光催化性能

采用溶胶-凝胶法制备ZnO纳米粒子,采用X-射线衍射仪(XRD)、透射电镜(TEM)等手段对样品进行了表征;以纳米氧化锌作为光催化剂,利用300W高压汞灯为光源对甲基橙溶液进行光催化实验。实验结果表明:以汞灯为光源,纳米ZnO为催化剂对甲基橙溶液进行光催化时,纳米ZnO的最佳投加量为0.1020g。     

基于电子顺磁共振的锌卟啉敏化TiO2光催化性机理的研究

为了研究锌卟啉/TiO₂复合光催化剂的光催化效率及电子转移问题, 本文采用溶胶凝胶法制备了锌卟啉/TiO₂的混合光催化材料, 并利用紫外可见光谱、电子顺磁共振谱对锌卟啉/TiO₂复合光催化剂进行了表征与分析. 采用溶胶凝胶法制备了锌卟啉-TiO₂的混合光催化材料, 通过比较纯P25型TiO₂和掺入质量比分别为0.2%, 0.5%, 0.9%锌卟啉敏化剂的锌卟啉/TiO₂混合光催化材料的紫外可见光谱图可知, 加入适量锌卟啉敏化剂可提高TiO₂对甲基橙溶液的降解效率, 过多的掺入锌卟啉敏化剂会导致TiO₂表面被敏化剂覆盖, 从而影响了其对光子的吸收, 降低TiO₂的光催化效率, 降低TiO₂的光降解率, 甚至低于纯TiO₂的光降解率. 应用电子顺磁共振技术对锌卟啉敏化TiO₂光催化剂的光催化机理进行了合理的解释, 当使用紫外可见光源对粉末样品进行辐照时, 锌卟啉受光辐照产生的激发态电子促进具有强氧化性的Ti³⁺和超氧根自由基的生成, 从而有效的促进了光生空穴-电子对的分离, 提高了TiO₂的光催化性能.     

金属离子对纳米TiO2悬浊液的光催化性能影响的光谱研究

以钛氧有机物为前驱体,利用微乳液法制备了纳米TiO2微晶。用X射线衍射(XRD)和红外光谱(FTIR)等测试技术对产物进行了表征,并就纳米TiO2悬浊液中加入金属离子后光催化降解甲基橙溶液进行了初步的研究。光谱分析表明,纳米TiO2悬浊液中加入Bi3 离子后对甲基橙溶液的光催化降解有很大的促进作用,Bi3 与TiO2质量比为1∶8及TiO2的浓度为1.6g·L-1时光催化活性最佳。     

强悬浮性纳米TiO2的制备、表征及光催化活性研究(Ⅱ)光催化活性研究

将甲基橙溶液作为模拟废水,考察了热分解制备纳米TiO2后处理过程中采用硅油淬火改性和自然冷却所得产物的光催化活性。结果表明：两者均具有良好的光催化降解效果,且活性差别不大。但经硅油淬火改性的纳米TiO2因在水中具有强悬浮性,可更为有效地利用外部光源在工业废水的表层降解有害成分。     

纳米ZnO-SiO2自清洁增透薄膜的制备及其性能

以乙酸锌醇热法ZnO纳米粒子为基料, 通过溶胶-凝胶浸渍提拉法制备纳米ZnO-SiO₂自清洁增透薄膜. 采用透射电镜, 光谱椭偏仪, 扫描电镜, X-射线衍射, 差热分析仪和UV-vis等技术对样品进行表征, 以亚甲基蓝的光催化降解为目标反应, 评价其光催化活性. 结果表明, ZnO纳米粒子为球粒状结构, 直径约12-20 nm, 特征紫外吸收波长位于375 nm 处; 与未涂覆纳米ZnO-SiO₂自清洁增透薄膜的石英玻璃基底相比, 涂覆后石英玻璃在400-800 nm波长范围内平均透光率提升达4.17%, 具有良好的宽光谱增透行为; 且在紫外光激发下对亚甲基蓝染料具有光催化降解特性, 进而具备良好的自清洁性能.     

DBU液相催化法原位合成四苯氧基酞菁锌/ZnO复合材料的制备及光催化选择性研究

在负载于氧化铟锡(ITO)导电玻璃上、哑铃状纳米ZnO表面配位未饱和锌离子作为“模板”,以苯氧基邻苯二腈作为“分子碎片”,利用DBU液相催化法,在亲水性纳米ZnO表面,原位合成疏水性四苯氧基酞菁锌(ZnTPPc)。通过多种表征手段,分析证实了所合成的ZnTPPc分子结构、ZnTPPc/ZnO界面及光生电荷转移特性。在可见光下,分别以亲水性亚甲基蓝(MB)、疏水性苯酚(PL)及其混合液为待降解反应物,定量分析疏水性ZnTPPc/ZnO复合材料对降解疏水性PL的光催化选择性。结果表明： 原位合成ZnTPPc在ZnO表面呈现单分子层,具有较好的疏水性能,ZnTPPc可优先选择性降解疏水性PL,且在可见光光催化中对PL的相对降解效率是对MB分子的1.21倍。     

水热法制备In2O3/ZnO异质结及其高的光催化性能

采用简单的两步水热法合成了不同In₂O₃质量比的In₂O₃/ZnO异质结复合材料．通过X射线衍射仪(XRD)、紫外-可见分光光度计(UV-vis)和扫描电子显微镜(SEM)对复合材料的结构、形貌和性能进行了表征．同时还使用UV-vis分光光度计测试了异质结降解罗丹明B(RhB)的光催化活性．实验结果表明,与纯ZnO和In₂O₃相比,In₂O₃的引入将ZnO的吸收光谱扩展到可见光区域,从而提高了其光生电子和空穴的分离．此外,In₂O₃/ZnO异质结在可见光照射对RhB具有较高的光催化活性．5 wt%-In₂O₃/ZnO异质结对RhB的降解率为84.3%,且具有良好的光催化稳定性．In₂O₃/ZnO异质结复合材料在有机染料废水的降解中有更广阔的应用前景．     

Photolysis of Diazo Dye in Solutions and Films Containing Zinc and Silver Oxides

Photolysis of Chicago Sky Blue diazo dye in aqueous solutions and films containing zinc and silver oxides is studied. The presence of zinc and silver nitrates in aqueous solutions of this dye considerably increase the rate of its photolysis under UV irradiation. ZnO and ZnO:Ag oxide films and composite coatings with zinc and silver nitrates also considerably affect the photolysis of Chicago Sky Blue diazo dye.     

A twice liquid arc discharge approach for synthesis of visible-light-active nanocrystalline Ag:ZnO photocatalyst

Ag:ZnO hybrid nanostructures were successfully prepared by a twice arc discharge method in liquid. The visible light photocatalytic activities were successfully demonstrated for the degradation of Rhodamine B (Rh. B), Methyl orange (MO), and Methylene blue (MB) as standard organic compounds under the irradiation of 90 W halogen light for 2 h. The Ag:ZnO nanostructures were characterized by X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible absorption spectroscopy (UV-Vis). The results revealed that the Ag:ZnO nanostructures extended the light absorption spectrum toward the visible region and significantly enhanced the Rh. B photodegradation under visible light irradiation. 3 mM Ag:ZnO nanostructures exhibited highest photocatalytic efficiency. It has been confirmed that the Ag:ZnO nanostructures could be excited by visible light (E<3.3 eV). The significant enhancement in the Ag:ZnO nanostructures photocatalytic activity under visible light irradiation can be ascribed to the effect of physisorbed noble metal Ag by acting as electron traps in ZnO band gap. A mechanism for photocatalytic degradation of organic pollutant over Ag:ZnO photocatalyst was proposed based on our observations.     

Synthesis and Spectral Characteristics for Zinc Tetraphenylporphyrin Modified Zinc Oxide NanowiresSynthesis and Spectral Characteristics for Zinc Tetraphenylporphyrin Modified Zinc Oxide Nanowires

A nest-like architectures(ZnO NAs)were prepared onto the conductive glass(ITO)by hydrothermal method.A metal-free porphyrin,tetraphenylporphyrin(H2TPP),was synthesized via Adler method.Zn ions with Zn-unsaturated coordination bonds on the surface of ZnO NAs were used as a template,and also H2TPP was used as"molecular fragments".Zinc tetraphenylporphyrin(ZnTPP)molecules were obtained on the surface of ZnO NAs by in-situ method.ZnO NAs direct provides of zinc source makes ZnTPP stably coated on the surface of ZnO NAs nanosheet,formed a tight composite materials(ZnTPP/ZnO NAs).Due toZnTPP with four phenyls in meso position,the surface of ZnTPP/ZnO NAs was with hydrophobic property.In the photocatalytic experiment,the degradation selectivity for phenol(hydrophobicity)in the mixture of phenol and rhodamine B(hydrophily)was increased under visible irradiation.     

Zinc oxide's hierarchical nanostructure and its photocatalytic properties

In this study, a new hierarchical nanostructure that consists of zinc oxide (ZnO) was produced by the electrospinning process followed by a hydrothermal technique. First, electrospinning of a colloidal solution that consisted of zinc nanoparticles, zinc acetate dihydrate and poly(vinyl alcohol) was performed to produce polymeric nanofibers embedding solid nanoparticles. Calcination of the obtained electrospun nanofiber mats in air at 500 °C for 90 min produced pure ZnO nanofibers with rough surfaces. The rough surface strongly enhanced outgrowing of ZnO nanobranches when a specific hydrothermal technique was used. Methylene blue dihydrate was used to check the photocatalytic ability of the produced nanostructures. The results indicated that the hierarchical nanostructure had a better performance than the other form.     

Zinc Oxide–Porphyrin Hybrid Rhombuses: Catalytically Active Microstructures via Self‐Assembly

A novel self‐assembled organic–inorganic hybrid structure consisting of zinc oxide and two oppositely charged porphyrins, showing significantly enhanced photocatalytic activity, is presented. Electrostatic self‐assembly of the cationic tetra‐(N‐methyl‐4‐pyridyl)porphyrin (TMPyP) with preformed assemblies of ZnO nanorods and the anionic tetra‐(4‐sulfonatophenyl)porphyrin (TPPS) in ethanol results in porphyrin microrhombuses decorated with ZnO nanorods. The structure formation is followed spectroscopically. The shape of the microrhombuses and the number of attached ZnO nanoparticles can be tuned through the porphyrin ratio TMPyP/TPPS. An enhanced and selective catalytic activity is found, giving insight into the degradation mechanism. Due to the tool‐box principle and its versatility, the concept may have great impact in fields such as solar‐energy conversion and optoelectronics.     

Sol-gel preparation and enhanced photocatalytic performance of Cu-doped ZnO nanoparticles

Cu-doped ZnO nanoparticles were prepared by a sol-gel method for the first time. XRD, XPS, UV-vis and FS techniques were used to characterize the Cu-doped ZnO samples. The photocatalytic activity was tested for methyl orange degradation under UV irradiation. The results show that the crystal sizes of ZnO and 0.5% Cu/ZnO nanoparticles with wurtzite phase are 32.0 and 28.5 nm, indicating that Cu-doping hinder the growth of crystal grains. The doped Cu element existed as Cu²⁺. The optimal Cu doping concentration in ZnO is 0.5%. The optimal calcination condition is at 350 °C for 3 h. The MO degradation rate of 0.5% Cu/ZnO reaches 88.0% when initial concentration of MO is 20 mg/L, exceeding that of undoped ZnO. The enhanced charge carrier separation and increased surface hydroxyl groups due to Cu-doping contributed to the enhanced photocatalytic activity of 0.5% Cu/ZnO.     

Synthesis and Photocatalytic Activity of One-dimensional ZnO-Zn2SnO4 Mixed Oxide Nanowires

采用简单的热蒸发方法得到具有不同尺寸的混合ZnO-Zn2SnO4 (ZnO-ZTO)纳米线,并对纳米线进行结构和成分分析,试验还以甲基橙溶液为处理对象考察了ZnO-ZTO纳米线的光催化活性.结果表明ZnO-ZTO 混合纳米线的光催化性较纯ZnO、纯Zn2SnO4纳米线有较大提高; 光催化剂浓度对光降解效率有很大影响, 与纯ZnO、纯Zn2SnO4纳米线相比,少量的ZnO-ZTO纳米线即达到较高的光催化效率;并且光催化活性随着纳米线直径的减小而增加. 实验表明异质结的存在能够加快电子空穴的分离,提高光催化活     

Effect of annealing temperature on photocatalytic activity of ZnO thin films prepared by sol-gel method

Zinc oxide thin films are deposited on Si and quartz substrates using the sol-gel method. The thin films, annealed at 400, 600 and 800 °C respectively, are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), ultraviolet-visible spectrophotometer (UV-Vis), fluorescence spectrometer (FL) and the photocatalytic activity is tested by the decomposition of methyl orange dye under UV illumination. The results show that the mean grain size, surface-to-volume ratio, rms roughness and degradation efficiency of the thin films increases with increasing annealing temperature. In particular, ZnO thin film annealed at 800 °C exhibits the highest photocatalytic activity, degrading methyl orange by almost 88% in 180 min. Photocatalytic reaction mechanism of the ZnO thin films is discussed in detail, and the oxygen defects are proposed to be the active sites of the ZnO photocatalyst.