La3+掺杂对纳米TiO2微观结构及光催化性能的影响

以钛酸丁酯和氯化镧为原料,采用溶胶-凝胶法制备了La3+掺杂TiO2纳米粉体,讨论了不同掺杂浓度、不同热处理温度的样品催化降解刚果红染料实验中的光催化活性,并通过X射线衍射(XRD)、透射电镜(TEM)分析了La3+掺杂TiO2样品的相组成、晶胞参数和晶粒大小对光催化活性的影响.结果表明:La3+掺杂能够显著提高TiO2粒子的光催化活性,最佳掺杂浓度为100∶3 0,最佳热处理温度为600℃;La3+掺杂的TiO2的相组成是影响光催化活性的决定性因素;晶格膨胀程度及晶粒大小对光催化活性的影响,主要是在相组成相同或相近时才体现得比较明显.     

环境友好型塑料用改性ZnO添加剂的光催化性能研究

以纳米ZnO和AgNO3溶液为原料,采用掺杂的方法制备了改性的塑料用ZnO添加剂,通过其光催化降解亚甲基蓝的效果评价了样品的光催化性能。实验结果表明,当银的掺杂量为2.8%,光催化剂添加浓度是0.8g/L时,此时Ag/ZnO复合粉体对亚甲基蓝的光催化降解效果最好。制备的Ag/ZnO复合粉体在紫外光区和可见光区都有较强的吸收,且吸收峰波长和Ag与纳米ZnO相比都出现了一定程度的红移。掺杂银显著提高了纳米ZnO的光催化性能     

掺铁纳米氧化锌的制备及其光催化性能

采用共沉淀法制备了纯纳米ZnO和掺铁纳米ZnO,并用X射线衍射光谱进行了表征。用紫外灯作为光源,甲基橙溶液为光催化反应模型降解物,研究了ZnO及掺铁ZnO的光催化性能,并考察了前驱体焙烧温度、铁掺杂量、底物浓度、光照时间以及pH对降解率的影响。结果表明,掺杂铁离子提高了ZnO的光催化活性,400℃热处理的掺杂铁0.5%(质量比)的ZnO的光催化性能最好;当甲基橙初始浓度为5mg/L,光照时间3h,掺杂铁0.5%(质量比)的ZnO粉末对甲基橙的降解率达到84%;掺铁纳米ZnO在弱酸性条件下的催化效果比碱性条件下更好。     

ZnO:Cd纳米棒的制备及其光催化降解性能研究

采用水热法制备了ZnO和不同Cd掺杂浓度的ZnO:Cd纳米棒。通过x射线衍射仪、扫描电子显微镜、紫外-可见-近红外分光光度计和拉曼光谱对ZnO:Cd纳米棒的结构和光学特性进行了系统研究。结果显示,样品为一维纳米棒结构,Cd的掺杂可以减小ZnO纳米棒的晶粒尺寸和光学带隙。利用分光光度计检测ZnO:Cd纳米棒对偶氮结构染料(甲基橙溶液)的光催化降解效率,结果表明Cd掺杂可以改善ZnO的光催化性能,掺杂浓度为16%时ZnO:Cd纳米棒对甲基橙溶液的光催化降解效率最高。     

均匀沉淀法制备ZnO、Fe/ZnO光催化剂

以六水合硝酸锌、九水合硝酸铁和CO(NH2)2为原料,采用均匀沉淀法并且改变实验条件制备了纯纳米ZnO和纳米Fe/ZnO光催化剂。通过X射线衍射(XRD)和扫描电子显微镜(SEM)对所有样品进行表征,并对部分样品进行了X射线能谱分析仪(EDS)测试。结果显示所有样品均为六方纤锌矿结构。此外,所有样品均由小颗粒聚集在一起而形成了形状、大小各不相同的团聚物或颗粒膜。而且随煅烧温度和Fe掺杂浓度的改变,Fe/ZnO样品的晶粒尺寸和表面形貌也随之变化。以甲基橙溶液作为污染物,在高压汞灯的照射下进行了光降解实验,实验结果表明:Fe掺杂Fe/ZnO样品的光催化性能相较纯纳米ZnO样品得到了改善。当Fe掺杂量为1.5%时Fe/ZnO样品的光催化性能最好;另外,适当煅烧温度也使Fe/ZnO样品的光催化活性得到了提升,其中最适煅烧温度为500℃。无论是Fe的掺杂浓度还是煅烧温度,适当的Fe的掺杂浓度和煅烧温度都有利于改善Fe/ZnO样品光催化剂的性能。     

高效Mn/ZnO-Ag纳米复合光催化体系的简易制备及研究

本研究使用简易高分子网络凝胶法制备了不同Mn含量掺杂的ZnO及Mn、Ag共掺的ZnO纳米光催化剂.在模拟太阳光下通过降解有机染料亚甲基蓝(MB)来研究样品的光催化性能.XRD和SEM证实,Mn的掺入减小了样品的晶粒尺寸,但改善了样品的颗粒分布.通过XPS能谱发现催化剂中存在Mn2+和Mn3+,且随Mn离子掺杂量的增加,Mn3+/Mn2+比例增大.PL光谱显示,Mn/ZnO-Ag体系的发光强度较纯ZnO显著降低,其中当Mn浓度为1％(摩尔分数)时展现出最高效的光生载流子分离.结果表明,Mn掺杂显著增强了ZnO对可见光的吸收,但在一阶光降解动力学方程中并未发现显著的光催化活性提升,而Mn/ZnO-Ag样品在保持较好光学性能的同时大幅提高了ZnO的光催化活性.结合光催化测试结果发现,Mn/ZnO-Ag样品光催化性能的提升与其对可见光利用率的提高、Mn离子间价态变化及Mn离子与Ag粒子间的协同作用有关.这为系统性提升ZnO的光催化活性提供了一种有用的途径.     

Ce/ZnO纳米复合抗菌剂的制备及其性能研究

以纳米氧化锌(ZnO)为载体,采用稀土离子掺杂的方法制备了Ce/ZnO纳米复合抗菌剂。通过TEM、XRD等技术对样品进行表征,结果表明:制备的Ce/ZnO复合粉体是一种纳米复合抗菌剂,粒径在20nm左右,并且铈以CeO2的化学态存在于Ce/ZnO复合粉体表面,在ZnO的位置上进行了有效掺杂。掺杂稀土铈有效的提高了纳米ZnO的光催化性能以及抗菌效果。     

ZnO:Sb3+纳米粉的制备及发光性能的研究

采用共沉淀法制备了六方纤锌矿结构的Sb3+掺杂ZnO纳米荧光粉,并系统研究了不同Sb3+掺杂浓度、不同煅烧温度和时间对其发光性能的影响.借助于XRD、SEM、荧光光度计等测试手段对粉体的相组成、形貌及其光致发光性能进行了表征.结果表明:掺杂Sb3+样品的粒度小于未掺杂样品的粒度,当Sb3+掺杂浓度小于3％时,ZnO:S...     

Fe、Ce单复合掺杂纳米氧化锌粉体的制备及其光催化性能研究

纳米ZnO材料因特殊的禁带宽度和开放性结构,易掺杂其他金属或者非金属元素,具有良好的催化性能。本文通过溶胶-凝胶法,制备了Fe、Ce单复合掺杂纳米ZnO粉体,对样品进行了表征分析,并以甲基橙为目标降解物,测定了单复合掺杂纳米氧化锌粉体在不同紫外光催化下的性能,考察了紫外灯强度、光照时间对催化效率的影响。结果表明,相比纯的纳米ZnO粉体、Fe、Ce单复合掺杂纳米ZnO的降解效果更好。当催化剂用量为3g/L、在紫外灯30W光照下、光照时间为4h,Fe/Ce共掺杂纳米ZnO材料的降解率可达12.31%。     

Mn掺杂花状ZnO的合成及其光催化特性研究

采用液相沉积法,在室温条件下制备了不同Mn掺杂浓度(0,0.25%,0.5%和1.0%(摩尔分数))的花状ZnO微结构。利用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对制备的花状ZnO微结构的物相及形貌进行表征。以甲基橙溶液作为光催化反应模型污染物,对不同浓度的Mn掺杂花状ZnO微结构的光催化性能进行了研究。实验结果表明,Mn在ZnO材料中以两种形态存在,即进入晶格以Mn2+形式替代Zn2+和以Mn3O4形式附着在ZnO材料表面。且Mn掺杂提高了花状ZnO微球结构的光催化活性,当掺杂浓度为0.25%(摩尔分数)时光催化性能最优,紫外光照2.0h后,对甲基橙的光催化降解率可达88.7%。     

Doping effects of Co(2+) ions on ZnO nanorods and their photocatalytic properties

A series of Zn(1-x)Co(x)O nanorods with dopant content ranging from x = 0.00 to 0.10 was prepared by a wet chemical method. All Zn(1-x)Co(x)O samples were investigated by x-ray diffraction, transmission electron microscopy, energy-dispersion x-ray line mapping analysis, and UV-visible absorption spectroscopy. It was found that Co(2+) ions were homogeneously substituted for Zn(2+) ions in ZnO nanorods. Rhodamine B degradation was used as a probe reaction to evaluate the effect of Co(2+) doping on ZnO nanorods and photocatalytic performance under UV light and visible light irradiation. Co(2+) ions acted as the trapping or recombination centers for electrons and holes, leading to a reduction in photodegradation efficiency under UV light illumination. Alternatively, Co(2+) ions enhanced the optical absorption and produced the photoinduced carriers under visible illumination in terms of two charge transfer transitions involving Co(2+) ions. Consequently, Co(2+) ions substituted in the lattice of ZnO nanorods significantly improved the visible light photocatalytic activity.     

ZnO/Ag/CdCO_3纳米复合光催化剂的制备及性能研究

采用配位均匀共沉淀法制备出ZnO/Ag/CdCO3纳米复合光催化剂,用TEM、XRD、FT-IR、ICP等对产物的形貌、微观结构及组成进行了表征,着重研究了反应物配比及Cd(NO3)2浓度对ZnO/Ag/CdCO3纳米复合光催化剂催化降解甲基橙光催化活性的影响规律,结果表明,n(Zn2+):n(Ag+):n(Cd2+)=21:1.76:1.75,Cd(NO3)2浓度为0.168mol·dm-3时制得的纳米复合光催化剂对甲基橙(MO)的降解率较ZnO/Ag提高51%,ZnO/Ag/CdCO3对MO的光催化降解符合一级反应动力学方程,表观速率常数为1.4551h-1,是ZnO/Ag的7倍。     

Ag~+掺杂FeVO_4光催化剂的制备及光催化性能

采用液相沉淀法制备了银(Ag+)掺杂钒酸铁(FeVO4)光催化剂。采用XRD、SEM、EDS、BET和XPS等手段对样品的性能进行了表征分析,并以甲基橙为目标降解物,考察了催化剂在节能灯照射下的光催化活性。结果表明,Ag的掺杂没有改变FeVO4晶型,但引起了晶格畸变和膨胀。适量Ag的掺杂可提高FeVO4的光催化性能,在所进行实验的条件下,钒酸银最佳掺杂量为1%(质量分数)时,掺杂后的Fe-VO4对甲基橙溶液的脱色率较未掺杂前提高21%左右。     

Photoluminescence quenching and photocatalytic enhancement of Pr-doped ZnO nanocrystals

This work reports the synthesis of novel praseodymium (Pr)-doped ZnO nanocrystals with excellent photocatalytic activity through modified solid-state reaction route. The impacts of doping on the wurtzite hexagonal structure are analysed with X-ray diffraction (XRD) and Raman spectroscopy. The production of defect levels and the formation of Urbach energy within the system are confirmed using photoluminescence (PL) techniques and UV/Vis diffuse reflectance spectroscopy, respectively. The linear relationship between Urbach energy and band gap energy is elucidated from UV/Vis spectroscopy analysis. The changes happened to morphology by doping were tackled using scanning electron microscopy (SEM). The concentration quenching effect of PL emission with Pr doping is explained in detail. A three-fold enhancement in the photocatalytic activity was achieved with optimum Pr incorporation in ZnO. This work successfully correlated PL quenching and enhanced photocatalytic activity with the defect production happened in ZnO system on Pr doping. The practical applicability of the photocatalyst was confirmed with a stability test.     

ZnO/g-C_(3)N_(4)复合光催化剂的制备及光催化还原U(Ⅵ)EI北大核心CSCD

以ZnO和三聚氰胺为原料,采用热聚合法制备ZnO/g-C_(3)N_(4)复合型光催化剂,并将其用于光催化还原U(Ⅵ)。通过SEM,XRD,XPS,PL,UV-Vis测试手段对样品的表面形貌、晶格结构、元素组成、光催化性能进行分析。结果表明:ZnO的掺杂降低光生电子与空穴的复合率,扩大材料对可见光的响应范围,使复合材料具有更高的光催化活性。在pH=5、投加量为0.5 g/L时,经过暗反应30 min和光反应30 min,对U(Ⅵ)的最高去除率可达97%。U(Ⅵ)可被还原为U(Ⅳ),光生电子e-是实现将U(Ⅵ)还原为U(Ⅳ)的主要因素。     

Photoinduced hydroxyl radical and photocatalytic activity of samarium-doped TiO(2) nanocrystalline

Sm(3+)-doped TiO(2) nanocrystalline has been prepared by sol-gel auto-combustion technique and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, and also UV-vis diffuse reflectance spectroscopy (DRS). These Sm(3+)-doped TiO(2) samples were tested for methylene blue (MB) decomposition and *OH radical formation. The analysis of *OH radical formation on the sample surface under UV irradiation was performed by fluorescence technique with using terephthalic acid, which readily reacted with *OH radical to produce highly fluorescent product, 2-hydroxyterephthalic acid. It was observed that the presence of Sm(3+) ion as a dopant significantly enhanced the photocatalytic activity for MB degradation under UV light irradiation because both the larger specific surface area and the greater the formation rate of *OH radical were simultaneously obtained for Sm(3+)-doped TiO(2) nanocrystalline. The adsorption experimental demonstrated that Sm(3+)-TiO(2) had a higher MB adsorption capacity than undoped TiO(2) and the adsorption capacity of MB increased with the increase of samarium ion content. The results also indicated that the greater the formation rate of *OH radical was, the higher photocatalytic activity was achieved. In this study, the optimum amount of Sm(3+) doping was 0.5 mol%, at which the recombination of photo-induced electrons and holes could be effectively inhibited, the highest formation rate of *OH radicals was, and thereby the highest photocatalytic activity was achieved.     

RGO/ZnO纳米棒复合材料的合成及光催化性能

采用水热合成法制备ZnO纳米棒及RGO/ZnO纳米棒复合材料。研究不同含量的RGO对RGO/ZnO纳米棒复合材料光催化活性的影响。采用X射线衍射仪(XRD)、场发射电子显微镜(FESEM)、光电子能谱仪(XPS)及漫反射紫外-可见吸收光谱(UV-Vis)检测手段对RGO/ZnO进行表征。结果显示:RGO与ZnO纳米棒成功复合。加入GO的含量不同,获得的RGO/ZnO样品在可见光区域的吸光度值不同。以甲基橙作为模拟污染物的光催化结果表明,RGO/ZnO复合材料具有高的紫外-可见光光降解效率,加入GO与ZnO的质量比为3%时,样品紫外-可见光光催化性能最佳,120min内甲基橙基本可以完全降解;且在波长大于400nm可见光照射下,RGO/ZnO具有一定的可见光活性,180min内其降解甲基橙效率最大可达26.2%。同时,RGO/ZnO具有较好的光稳定性。     

Enhanced ferromagnetic and photocatalytic properties in Mn or Fe doped p-CuO/n-ZnO nanocomposites

Mn doped CuO/ZnO heterostructure exhibited significant room temperature ferromagnetism and visible light photocatalytic properties. Phase analysis for the pure, Mn and Fe doped CuO/ZnO nanocomposites evidently confirmed the formation of CuO and ZnO phases in each composite without any impurities. Based on Rietveld refinement analysis, the inclusion of Mn ions into CuO/ZnO nanocomposite decreased the unit cell volume of both oxides while Fe ions lead to lattice expansion. Mn ions induced the formation of ZnO hexagonal nanorods in CuO/ZnO nanocomposite. Nano-flakes and spherical nanoparticles shapes were seen for Fe doped CuO/ZnO nanocomposites. The characteristics IR absorption bands of CuO and ZnO overlapped together in their nanocomposites structure. From Kubelka-Munk plots, the incorporation of Mn ions enabled the ZnO band gap to absorb in the visible light region. Pure CuO/ZnO nanocomposite exhibited room temperature ferromagnetism with saturation magnetization (M_s) of 0.042 emu/g and coercivity (H_c) of 547 Oe. The ferromagnetic properties of the pure CuO/ZnO nanocomposite were greatly improved by Mn and Fe doping and the saturation magnetization extremely jumped to 0.86 and 0.85 emu/g, respectively. High photocatalytic activity, 98%, with good reusability for methyl orange (MO) degradation under visible light irradiation was achieved by 4 wt% Mn doped CuO/ZnO nanocomposite. A relation between the crystallinity, band gap and photocatalytic activity with dopant type (Mn or Fe) incorporated into CuO/ZnO nanocomposites was noticed. In contrary to Fe dopant, Mn as dopant played successful roles in improving the crystallinity, band gap and photocatalytic properties of CuO/ZnO nanocomposite. Multifunctional properties can be realized by combining different oxides in heterostructure form and using doping technique.