铕掺杂的TiO2空心微球的制备及光催化性能

通过溶胶-凝胶法制备未掺杂和铕掺杂的TiO₂空心微球, 采用XRD、SEM、TEM、HRTEM、BET和XPS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, 钛酸四丁酯(TBOT)的加入量对微球的形貌影响较大, 当滴加1.5 mL的TBOT时, 可得结构清晰、分散性良好的TiO₂空心微球。XRD分析表明, 400℃煅烧的纳米TiO₂空心微球为锐钛矿, 掺铕可抑制TiO₂的晶相转变。光催化实验表明, 铕掺杂能显著提高TiO₂空心微球的活性。当铕掺量为0.7%时, 所得样品粒径和孔径最小, 比表面积最大, 光催化活性最高。     

SiO2@TiO2核壳微球和TiO2中空微球的制备及其光催化性能

以Stber法制备的单分散SiO_2微球为模板,率先采用静电吸附法和相吸附法相结合技术制备出SiO_2@TiO_2核壳结构微球。深入研究了pH值及煅烧温度对其结构和性能的影响。对SiO_2@TiO_2微球进行去核处理,得到TiO_2中空微球。通过降解常见工业污染物硝基苯来研究两种微球的光催化活性。采用XRD、SEM、TEM、BET、FT-IR对样品进行表征,用紫外-可见分光光度计测量硝基苯溶液降解前后的吸光度。结果表明,相同条件制备的TiO_2中空微球的比表面积比SiO_2@TiO_2微球的显著增大,最大为87m~2/g,导致TiO_2中空微球的光催化活性比SiO_2@TiO_2微球明显提高,对硝基苯的4h降解率可达95.2%。低于600℃处理得到的TiO_2壳层为锐钛矿相,呈孤岛状模式生长。温度升高到700℃时出现金红石相。在pH=9.0、600℃热处理3h条件下制备的SiO_2@TiO_2微球经去核处理所得到的TiO_2中空微球的壳层厚度最大,为25.4nm,且空心球的Ti-O-Si键随之消失。     

Fe~(3+)/Ti~(4+)赋存状态对钛酸铝/莫来石复合材料结构的影响

借助XRD、SEM和能谱分析仪等手段,研究了1 600℃煅烧中低品位矾土制备的钛酸铝/莫来石(Al_2TiO_5ss/3Al_2O_3·2SiO_2ss)复合材料经1 200℃保温12h后结构的稳定性。结果表明:高温煅烧中低品位矾土后,其合成材料的结晶物相组成为3Al_2O_3·2SiO_2ss、Al_2TiO_5ss和少量残存的方石英;Fe~(3+)或Ti~(4+)离子以不同形态赋存于结晶相(3Al_2O_3·2SiO_2ss和Al_2TiO_5ss)和非晶相。含Fe~(3+)/Ti~(4+)离子的3Al_2O_3·2SiO_2ss将Al_2TiO_5ss结晶相分割,使其蜷缩其间,并抑制Al_2TiO_5ss的分解;高温下,二者因组成元素相近而致使晶界融合,进而共同构建了体系牢固的致密骨架结构。由3Al_2O_3·2SiO_2ss和Al_2TiO_5ss等高温物相构成的致密结构将非晶相挤压于空隙结构的3Al_2O_3·2SiO_2ss晶间,避免了低熔点相富集带来的不利影响,进而赋予该Al_2TiO_5ss/3Al_2O_3·2SiO_2ss复合材料良好的结构稳定性。     

金属离子掺杂TiO_2光催化降解甲基橙的研究

采用溶胶-凝胶法,以钛酸正丁酯为前驱物,无水乙醇为溶剂,冰醋酸为螯合剂,控制反应温度为40℃,pH=2~3,控制不同原料配比和煅烧温度,制备二氧化钛(TiO_2),及制备Cu~(2+)、Fe~(3+)、Zn~(2+)、Sr~(2+)、Na~+、Co~(2+)掺杂的TiO_2光催化剂,每种金属离子掺杂质量分数为0.2%。结果表明,最佳条件为钛酸正丁酯∶无水乙醇∶蒸馏水∶冰醋酸(体积比)=1∶10∶3∶1,煅烧温度为600℃;金属离子掺杂量相同的情况下,光催化降解甲基橙的顺序为:Fe-TiO_2Cu-TiO_2Na-TiO_2CoTiO_2Sr-TiO_2TiO_2Zn-TiO_2。     

Ag-TiO_2空心复合微球制备及其光催化性能

为了提高空心TiO2的光催化活性和拓展其对可见光的响应,以聚苯乙烯为模板合成TiO2空心微球,再通过KBH4还原AgNO3,制备了TiO2空心壳层表面载有Ag单质粒子的复合微球。利用SEM、TEM、XRD和EDS对Ag-TiO2空心微球的形貌结构和组成进行表征,并以有机染料罗丹明B(RhB)为目标降解物,研究该复合微球的光催化性能。在紫外光下,载银量为2%的Ag-TiO2复合微球2h内对RhB的降解率比同条件下空心TiO2提高23.8%;在可见光下,载银量为2%的Ag-TiO2复合微球在6h内对RhB的降解率比同条件下空心TiO2提高28.2%。结果表明,壳层表面载有适量Ag单质粒子的空心TiO2复合微球,其光催化活性和对可见光的响应显著高于纯空心TiO2微球。     

氧化铈空心微球的制备及表征

通过聚合物模板法和高温煅烧法制备了氧化铈空心微球,并考察了其光催化性能。采用透射电镜(TEM)和扫描电镜(SEM)研究氧化铈空心微球的尺寸和微观形貌,通过傅立叶转换红外线光谱(FTIR),X射线衍射(XRD)和比表面积(BET)表征空心微球、晶型结构、比表面积。结果表明,以粒径为220nm的聚苯乙烯微球可以制得球径约为220nm的CeO_2空心微球。壳层厚度约为20nm。在模拟可见光的条件下,氧化铈空心微球对罗丹名B的降解率在3h内可达到95%以上,表现出优异的光催化降解性能。     

Fe~(3+)/N共改性TiO_2可见光催化剂的制备及其对染料光催化降解性能研究

以偕胺肟纤维(AOCF)为载体,与TiCl_4进行配位后再水解,制得TiO_2/纤维复合物(N-TiO_2)。再将NTiO_2与FeCl_3反应,获得Fe、N共改性纳米TiO_2/纤维复合材料(Fe3+/N-TiO_2)。采用SEM、XRD、EDS等对复合物的形貌、晶态结构、表面元素进行表征。以染料降解率为指标,优化制备条件:Fe~(3+)初始浓度5.0mmol/L、pH=2.0、改性反应时间为20min。考察了Fe~(3+)/N-TiO_2对活性黄、活性红和甲基橙三种染料溶液的光催化降解性能,结果显示:在可见光下其对3种染料表现出良好的光催化性能,且可多次重复使用与再生,光催化反应过程符合一级反应动力学特征。PL和UV-Vis分析表明:Fe、N共改性使TiO_2禁带宽度窄化,吸收带边红移,其光谱响应范围变宽。     

稀土Dy掺杂对纳米TiO2相变及光催化性能的影响

采用溶胶-微波法制备了稀土元素Dy掺杂的纳米TiO_2复合粉体,采用XRD、拉曼、XPS等手段对样品进行了表征和分析,并以甲基橙的光催化降解为探针反应,探讨稀土Dy掺杂对纳米TiO_2的相变及光催化活性的影响。研究结果表明:稀土掺量为1.3%、经550℃煅烧后制备的样品光催化活性显著提高,对甲基橙的降解率为92%。与未掺杂纳米TiO_2相比,稀土Dy掺杂可以阻碍纳米TiO_2晶粒的生长,增大了比表面积;提高其热稳定性,抑制TiO_2锐钛矿相向金红石相转变;并使TiO_2产生晶格缺陷从而增加纳米TiO_2粉体表面羟基含量和表面氧空位,抑制了光生电子和空穴的复合,增强纳米TiO_2的光催化活性。     

暴露高能晶面TiO_2空心微球的制备及其光催化性能

目前二氧化钛(TiO_2)空心微球制备方法主要为模板法,步骤繁琐,模板难去除。采用一步水热法制备暴露(001)晶面的TiO_2空心微球,水热温度为200℃,水热时间12h,通过改变氟和钛的物质的量的比来控制TiO_2的形貌。采用XRD、FESEM、TEM、EDS等方法对样品的晶体结构、微观形貌进行表征。以罗丹明B为模拟污染物,采用紫外分光光计测定污染物的吸光度,评价了样品紫外光光催化降解罗丹明B的活性,当氟和钛的物质量的比值为2时,制备得到具有暴露(001)晶面的TiO_2空心微球,并且表现出了最佳的光催化活性。光催化反应40min,对10mg/L的罗丹明B的降解率达到95%。     

N掺杂介孔TiO2柠檬酸催化合成及其光催化性能研究

采用柠檬酸酸催化溶胶-凝胶法合成了N掺杂介孔TiO_2,并用XRD、HRTEM、XPS、BET、UV-vis等手段表征了N-TiO_2。测试结果表明,煅烧前的样品是无定形TiO_2,低温煅烧后的产物是锐钛矿TiO_2,而750℃煅烧产物是金红石型。少量N元素的掺杂致使TiO_2的吸收带边位置发生少许红移,移向可见光区域。N_2吸附-脱附和光解甲基橙结果显示,N掺杂介孔TiO_2(3.0 at.%)的BET面积为102 m~2/g,孔尺寸大小约为9.8 nm,具有比P25更强的光催化降解甲基橙的能力。     

Preparation and characterization of magnetically separable photocatalyst (TiO2/SiO2/Fe3O4): effect of carbon coating and calcination temperature

TiO2/SiO2/Fe3O4 composite was synthesized by sol-gel technique for silica and titania coatings on magnetite core to enable recovery after photocatalytic degradation. Carbon coating was also carried out by calcination of TiO2/SiO2/Fe3O4 under nitrogen atmosphere in presence of PVA as a source of carbon to enhance the adsorption of organic compounds on catalyst surface and to get better activity. All prepared samples were characterized using EDX, CN analyzer, XRD, BET and SEM. Degradation of methyl orange dye was used to assess the photocatalytic performance of the prepared samples. Calcination temperature was found to affect rate of reaction because of the formation of rutile phase at high calcination temperature. Carbon coated samples unexpectedly exhibited lower rate of reaction at almost all calcination temperatures.     

静电纺丝法制备Fe3+/TiO2纳米纤维及表征

以聚乙烯吡咯烷酮(PVP)为纤维模板,钛酸四丁酯(Ti[O(CH2)3CH3]4)和Fe3+为前驱体,乙醇为溶剂,醋酸为催化剂,采用静电纺丝法制备不同含铁量的复合纳米纤维Fe3+/TiO2,经500℃煅烧得到以锐钛矿为主的Fe3+/TiO2纳米纤维。采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)分别表征了Fe3+/TiO2纳米纤维的形貌与晶态,计算了样品的晶粒尺寸和锐钛矿所占的比例,并比较了5%Fe3+/TiO2纳米纤维、5%Fe3+/TiO2粉体以及纯TiO2纳米纤维三者光催化降解亚甲基蓝(MB)的效果。研究表明:由静电纺丝法制备的5%Fe3+/TiO2纳米纤维的光催化降解效果比相同含铁量的粉体的降解效果好,TiO2纳米纤维比5%Fe3+/TiO2纳米纤维的光催化活性高。     

超临界流体干燥法制备TiO2/ Fe2O3 和TiO2/ Fe2O3/ SiO2 复合纳米粒子及光催化性能

以TiCl₄ 、Fe (NO₃ )₃·9H₂O 和Na₂SiO₃19H₂O 为原料, 采用溶胶凝胶法结合超临界流体干燥法(SCFD)制备了纳米级TiO₂/ Fe₂O₃ 和TiO₂/ Fe₂O₃/ SiO₂ 复合光催化剂。以光催化降解苯酚对所得催化剂的催化活性进行了评价。结果表明, 纳米TiO₂/ Fe₂O₃ 复合粒子与单组分TiO₂ 比较, 复合粒子光催化活性高于单组分的TiO₂, 6h 苯酚降解率高达95.9 %。SiO₂ 的加入可以抑制纳米粒子粒径的长大和晶相的转变, 增强TiO₂ 纳米粒子的热稳定性。复合光催化剂中Fe₂O₃ 最佳掺入量为0.06 %, SiO₂ 最佳掺入量为10 %(摩尔分数) 。并用XRD、TEM 和FTIR 等手段进行了表征。TiO₂ 以锐钛矿型形式存在, SiO₂ 以无定性形式存在。比较了不同制备方法制得的TiO₂/ Fe₂O₃ 复合光催化剂, 得出超临界干燥法制备的光催化剂具有粒径小、比表面积大、分散性好、光催化活性高等特点。采用超临界流体干燥可直接得锐钛型纳米复合光催化剂。     

磁性纳米TiO2/SiO2/Fe3O4光催化剂的制备及表征

以纳米Fe3O4磁粉为核心，采用溶胶一凝胶法制备了TiO2／SiO2／Fe3O4复合光催化剂．用XRD、TEM及元素分析对其结构和表面形貌进行了表征．以具有偶氮染料结构的甲基橙水溶液为目标反应物，评价其光催化活性．结果表明，所制TiO2／SiO2／FeaO4样品为双层包覆型结构，SiO2为中间层，最外层是锐钛矿型的TiO2,该复合光催化剂对甲基橙溶液有较高的光催化活性，并具有可利用其磁性回收重用的特点，应用前景广泛。     

Microwave absorption enhancement of multifunctional composite microspheres with spinel Fe3 O4 Cores and Anatase TiO2 shells

Multifunctional composite microspheres with spinel Fe(3)O(4) cores and anatase TiO(2) shells (Fe(3)O(4)@TiO(2)) are synthesized by combining a solvothermal reaction and calcination process. The size, morphology, microstructure, phase purity, and magnetic properties are characterized by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, selected-area electron diffraction, electron energy loss spectroscopy, powder X-ray diffraction, and superconducting quantum interference device magnetometry. The results show that the as-synthesized microspheres have a unique morphology, uniform size, good crystallinity, favorable superparamagnetism, and high magnetization. By varying the experimental conditions such as Fe(3)O(4) size and concentration, microspheres with different core sizes and shell thickneses can be readily synthesized. Furthermore, the microwave absorption properties of these microspheres are investigated in terms of complex permittivity and permeability. By integration of the chemical composition and unique structure, the Fe(3)O(4)@TiO(2) microspheres possess lower reflection loss and a wider absorption frequency range than pure Fe(3)O(4). Moreover, the electromagnetic data demonstrate that Fe(3)O(4@TiO(2) microspheres with thicker TiO(2) shells exhibit significantly enhanced microwave absorption properties compared to those with thinner TiO(2) shells, which may result from effective complementarities between dielectric loss and magnetic loss. All the results indicate that these Fe(3)O(4)@TiO(2) microspheres may be attractive candidate materials for microwave absorption applications.     

Preparation of Fe3+-doped TiO2 catalysts by controlled hydrolysis of titanium alkoxide and study on their photocatalytic activity for methyl orange degradation

Fe3+-doped TiO2 (Fe-TiO2) porous microspheres were prepared by controlled hydrolysis of Ti(OC4H9)4 with water generated "in situ" via an esterification reaction between acetic acid and ethanol, followed by hydrothermal treatment. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), electron paramagnetic resonance (EPR) spectrum, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and nitrogen adsorption-desorption methods. All of the undoped TiO2 and Fe-TiO2 samples exclusively consist of primary anatase crystallites, which further form porous microspheres with diameters ranging from 150 to 500 nm. The photocatalytic activity of Fe-TiO2 catalysts was evaluated from the photodegradation of methyl orange (MO) aqueous solution both under UV and visible light irradiation. Fe3+ doping effectively improves the photocatalytic activity under both UV light irradiation and visible light irradiation with an optimal doping concentration of 0.1 and 0.2%, respectively. The photocatalytic mechanisms of Fe-TiO2 catalysts were tentatively discussed.     

煅烧温度对TiO_2中空微球光催化性能的影响

以分散聚合法制得的单分散阳离子聚苯乙烯（PS）微球为模板,钛酸丁酯为前驱体,采用溶胶-凝胶法在模板表面包覆TiO2壳层,并在不同煅烧温度下制备了晶相结构不同的微米级中空TiO2微球。采用TEM、SEM、FT-IR、XRD、UV-Vis DRS对样品的微观结构、相态组成及光催化性能进行了表征。结果表明TiO2中空微球平均粒径达到1.23μm,壳层厚度约为30nm;随着煅烧温度增加,锐钛矿晶粒尺寸会增加,并在700℃时出现混晶结构;在500℃煅烧得到的TiO2中空微球对甲基橙（MO）降解表现出比P25更好的光催化性能及光催化稳定性。     

Preparation, characterization, and photocatalytic activity of Gd3+ doped TiO2 nanoparticles

TiO2 and Gd3+ doped TiO2 nanoparticles were prepared by sol-gel method and the materials were characterized by XRD, TEM, SEM-EDX, BET, FT-IR, UV-Vis absorption, and Raman spectral analysis. The photocatalytic activity of nano TiO2 and Gd/TiO2 nanoparticles was evaluated using a model pollutant propoxur, a carbamate pesticide, in a batch type UV photoreactor. The results revealed higher photocatalytic activity for Gd/TiO2 nanoparticles than both TiO2 nanoparticles and commercial TiO2 (Degussa P-25). The enhanced photocatalytic activity of Gd/TiO2 relative to TiO2 is attributed to its increased band gap energy as evidenced from the blue shift to shorter wavelength observed in the UV-Vis abso4ption spectra. The recombination rate of photogenerated electron-hole pair decreased due to increase in the band gap, which enhanced the charge transfer efficiency of Gd/TiO2 nanoparticles. Gd3+ with its half filled 7 f subshell facilitated rapid electron transfer at solid-liquid interface by shallowly trapping the electrons. Among the various dopant level of gadolinium, 0.3 wt% Gd/TiO2 nanoparticles showed higher activity than others due to its higher surface area.