铕掺杂对纳米TiO2的光催化活性的影响

用溶胶-凝胶法制备了掺杂Eu3+的纳米TiO2,用XRD和TG-DTA对其进行了表征,并以正庚烷为气相有机污染物的实例研究了样品的光催化活性,发现Eu3+进入TiO2晶格中引起了TiO2晶格膨胀,导致晶格畸变增大,抑制了TiO2晶相的转变和粒径的增长.结果表明,Eu3+掺杂可提高TiO2的光催化活性,并且当掺杂摩尔分数为0.3%时,光催化活性最好.随着焙烧温度的升高,光催化活性下降,而利用较高的水解酸度则有利于得到光催化活性较高的样品.     

掺杂镨的纳米二氧化钛光催化降解2,4-二硝基苯酚的研究

以钛酸丁酯为原料,用溶胶-凝胶(sol-gel)法制备了掺杂镨的纳米TiO2粉末.采用X光衍射仪对粉体的物相进行了表征.样品经500 ℃焙烧2 h后,0.5%(摩尔分数)Pr3+-TiO2纳米粉末为单一的锐钛型结构.通过粉体对2,4-二硝基苯酚的降解情况对其光催化活性进行了测试,结果表明与纯TiO2相比,Pr3+-TiO2的光催化活性有较大提高,当Pr3+的掺入量为0.5%(摩尔分数)时催化活性最高.以高压汞灯为光源,2,4-二硝基苯酚的初始浓度为50 mg·L-1,催化剂0.5%(摩尔分数)Pr3+-TiO2投加量为1.0 g·L-1时,2,4-二硝基苯酚的光催化降解效果最好.     

钕掺杂对纳米TiO2光催化分解水制氢活性的影响

 采用溶胶-凝胶法制备了一系列纳米TiO2和掺杂Nd3+ 的纳米TiO2光催化剂,并通过XRD, UV-Vis, TEM和N2吸附等技术对其进行了表征和分析,考察了样品光催化分解水制氢的活性. 结果表明, Nd3+的掺杂使TiO2的相变温度从600 ℃提高到800 ℃, 同时有效抑制了TiO2的粒径增长,提高了粒子的分散性和样品的比表面积, Nd3+掺杂量越大,催化剂的比表面积越大. 掺杂Nd3+ 后, TiO2的光催化制氢活性提高,本实验中Nd3+的最佳掺杂量为0.1%, 此时催化剂的活性比未掺杂TiO2提高了3.5倍. 随着焙烧温度升高, TiO2和Nd3+/TiO2样品的光催化活性均下降,但同时一定量的金红石相与锐钛矿相共存所产生的协同效应也使样品的光催化活性有所提高.     

铈掺杂TiO2光催化剂的制备及其催化性能

以TiCl4为原料、Ce(NO3)3·6H2O为稀土掺杂剂,制备了不同掺杂量的Ce/TiO2粉体,并进行了DTA-TG,XRD,SEM和TEM表征.实验主要考察铈掺杂对TiO2粉体的表面形状和光催化活性的影响.结果表明,掺铈能明显改善样品的团聚状态,有利于样品比表面积的增大.SEM和TEM对500℃的焙烧样品表征结果,掺杂样品二次颗粒的成孔性远好于没有掺杂的纯样品.掺杂量从m(CeO2)=0.5%增加到m(CeO2)=8%,样品的比表面积增加了74m2·g-1;活性评价结果表明,掺杂铈可有效提高催化剂的光催化活性,其中m(CeO2)=1%的样品活性最好.     

铈掺杂TiO2光催化剂的制备及其催化性能

以TiCl4为原料、Ce(NO3)3·6H2O为稀土掺杂剂,制备了不同掺杂量的Ce/TiO2粉体,并进行了DTA-TG,XRD,SEM和TEM表征.实验主要考察铈掺杂对TiO2粉体的表面形状和光催化活性的影响.结果表明,掺铈能明显改善样品的团聚状态,有利于样品比表面积的增大.SEM和TEM对500℃的焙烧样品表征结果,掺杂样品二次颗粒的成孔性远好于没有掺杂的纯样品.掺杂量从m(CeO2)=0.5%增加到m(CeO2)=8%,样品的比表面积增加了74m2·g-1;活性评价结果表明,掺杂铈可有效提高催化剂的光催化活性,其中m(CeO2)=1%的样品活性最好.     

Zn-TiO2/AC复合催化剂的制备及其光催化活性

以硝酸锌、钛酸四丁酯和活性炭为原料,采用真空吸附法制备了不同组成的Zn TiO₂/AC.通过X射线衍射(XRD)和透射电镜(TEM)对催化剂进行了表征.选择较难降解的Cl₃CCOOH作为探针分子考察了其光催化活性.结果表明,掺锌能提高TiO₂/AC的催化活性,当Zn的摩尔分数为0.5%(相对TiO₂)、处理温度为400℃,溶液的pH值为6时,Zn TiO₂/AC催化剂具有很好的光催化活性.     

掺铁TiO2气相光催化降解正己烷的研究

利用钛酸丁酯水解浸渍、共沉淀、水热等方法制备了掺铁TiO2纳米复合粉体材料并通过XRD、BET、TEM等手段作了表征，研究了掺铁TiO2对气相光催化降解正己烷反应的活性并和商品TiO2 Degussa P-25作了比较，考察了制法、掺铁量、焙烧温度等的影响。结果表明，和大多数液相反应不同，铁的掺入抑制了TiO2对正己烷的气相光催化降解。水热处理能较大程度地改善掺铁和未掺铁TiO2的光催化性能。P-25对正己烷的气相光催化活性则明显小于未掺铁TiO2样品，也小于某些掺铁样品。     

掺杂镧的TiO2纳米粒子的光致发光及其光催化性能

采用溶胶-凝胶法制备了纯的和掺杂La的TiO2纳米粒子,并利用XRD,TEM,XPS和荧光光谱(FS)等对样品进行表征,主要考察焙烧温度和La含量对TiO2纳米粒子的性质以及光催化降解苯酚活性的影响,并探讨了La的掺杂对TiO2相变的作用机制以及FS光谱与光催化活性的关系.结果表明,适量La掺杂能够提高TiO2纳米粒子FS光谱强度,这是因为La掺杂能够使表面氧空位和缺陷的浓度增加;600℃热处理的掺杂不同量La的TiO2样品的光催化活性顺序是:1%＞1.5%＞3%＞0.5%＞5%＞0%,这与它们的FS光谱强度的顺序是一致的,即FS光谱强度越高,其光催化活性越高.这是因为在光致发光过程中,FS信号主要来源于表面氧空位和缺陷,而在光催化反应过程中,表面氧空位和缺陷能够有利于光生电子被捕获.     

Fe掺杂对纳米TiO2薄膜的结构与光催化性能的影响

采用溶胶-凝胶法制备了Fe掺杂的TiO2薄膜,利用X射线光电子能谱、X射线衍射技术、显微共聚焦拉曼光谱、紫外可见光谱和原子力显微镜等对薄膜进行表征,以甲基橙为反应模型对光催化活性进行测试。 结果表明,在300~600 ℃焙烧时,TiO2以锐钛矿结构存在,700 ℃焙烧时出现金红石结构。 随掺铁量和焙烧温度的增加,Fe/TiO2薄膜的表面粗糙度和晶粒尺寸均逐渐增大;随镀膜层数的增加,Fe/TiO2薄膜光谱吸收向可见光方向移动;较低含量的铁掺杂改善了TiO2薄膜的光催化活性,而较高含量的铁掺杂则使TiO2薄膜的光催化活性下降,掺铁量为0.1%时Fe/TiO2薄膜的光催化活性最好。     

一步法水热合成 TiO2纳米线及其光催化性能

以钛酸丁酯和异丙醇为原料, 采用一步法在NaOH溶液中水解后直接进行水热反应, 经焙烧处理, 得到TiO2纳米线. 采用扫描电子显微镜(SEM)、X射线衍射(XRD)和能谱分析(EDX)对产物进行了形貌、结构及成分的表征. 考察了不同水热温度、碱液浓度、水热反应时间及焙烧温度等因素对产物的影响. 结果表明, 获得较好形貌TiO2纳米线的最佳水热温度、碱液浓度和水热反应时间分别是180 ℃, 10 mol/L和24 h. 所得TiO2纳米线焙烧至950 ℃时仍为锐钛矿相, 说明本文制备方法迟滞了TiO2纳米线由锐钛矿相向金红石相的转变. 以甲基橙为目标降解物, 采用紫外-可见分光光度计研究了未掺杂和铕掺杂TiO2纳米线(Eu-TiO2)的光催化性能. 结果显示, 最佳掺铕量(摩尔分数)为1.6%. 在300 W紫外灯照射60 min时, 此掺铕量的TiO2纳米线对甲基橙溶液的降解率是未掺杂样品的1.5倍.     

磁功能性TiO2光催化剂的制备及特性

采用溶胶-凝胶法以Fe₃O₄为磁核制备了磁功能性光催化剂,以甲基橙为模拟污染物,考察了掺杂Fe比例、催化剂煅烧温度以及煅烧时间对催化剂活性的影响.催化剂的最佳制备条件为:Fe₃O₄掺杂Fe含量为5%,煅烧温度为450 ℃,煅烧时间为2 h.通过TG-DTA、XRD、UV-Vis、TEM对催化剂进行了表征,结果表明:制备的催化剂具有明显的核壳结构,原Fe₃O₄磁核经过高温煅烧被氧化;TiO₂包覆在磁核表面;催化剂的吸收带边发生红移,在可见光区的吸收强度有所增强;催化剂颗粒的平均粒径为20 nm.     

铋掺杂介孔二氧化钛的制备及光催化动力学

以介孔分子筛(KIT-6)为载体,采用溶液浸渍法合成了铋(Bi)掺杂的介孔二氧化钛(TiO₂)光催化剂。利用XRD、TEM、SEM、XPS、N₂吸附-脱附法和拉曼光谱法等技术手段对材料的结构和形貌进行表征。通过紫外-可见吸收光谱法考察了催化剂对罗丹明B光催化降解效率,进一步考察了Bi的掺杂量对光催化反应速率的影响,并对光催化降解动力学进行了初步研究。结果表明,Bi掺杂的介孔TiO₂具有较窄的孔径分布(3~4 nm),而且吸收范围扩展到可见光区,其光催化活性明显高于商品TiO₂(P25)。随之Bi掺杂量的提高,反应速率常数也增大,其光催化降解罗丹明B的反应均符合准一级动力学方程。     

The effect of lanthanide on the degradation of RB in nanocrystalline Ln/TiO2 aqueous solution

A series of Nd³⁺, Pr³⁺, Er³⁺, and Dy³⁺ (0.25–5 at.%) homogeneously doped nanocrystalline titanium dioxides (Ln/TiO₂) were prepared by an easy sol–gel technique, and the roles of lanthanide doping on the photocatalytic activity in the degradation of rhodamine B (RB) in aqueous solution were studied. Both the concentration of the lanthanide dopant and calcination temperature showed significant effect to the photodegradation of RB. The photocatalytic activity of pure titania was drastically decreased when calcination temperature was at 700 °C, while the high photocatalytic activity was still maintained for lanthanide-doped samples. HPLC-MS method was used to study the degradation process, and it is demonstrated that the degradation of RB catalyzed by Ln/TiO₂ was principally go through with a stepwise de-ethylation photochemical process.     

脉冲激光沉积制备SrSn1-xCoxO3外延薄膜的微结构表征及能带调控

钙钛矿结构SrSnO₃因其独特的介电和半导体性质而备受关注,通过掺杂可显著调控其电学、磁学性能,拓宽其应用范围。本研究在单晶SrTiO₃(001)衬底上通过脉冲激光方法外延生长了SrSn_1-xCo_xO₃ (x = 0, 0.16, 0.33, 0.5) (SSCO)薄膜,探究了Co含量对薄膜结晶性、微观结构、光学性能以及介电性能的影响。结果表明, SrSn_1-xCo_xO₃薄膜可在SrTiO₃(001)衬底上外延生长, Co掺杂不会导致薄膜结晶质量的劣化。薄膜表面形貌平整、致密,膜厚200 nm,表面粗糙度为0.44 nm。随薄膜中Co掺杂量增加,薄膜透过率从90%降至25%,光学带隙从4.24 eV降至2.44 eV。介电性能测试表明,掺杂薄膜在10⁶Hz时介电常数为70.1,比无掺杂SrSnO₃薄膜提高57%。室温时SSCO薄膜表面电阻率为172 MΩ,在1000℃范围内薄膜结构稳定。     

Characterization and photocatalytic properties of silver and silver chloride doped TiO2 hollow nanoparticles

Using polystyrene（PSt） particles as template,PSt/TiO₂ composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO₃ and NaCl.AgCl doped TiO₂ hollow particles were successfully prepared with the PSt/TiO₂ composite microspheres pretreated at 180℃followed by calcination.The morphology of PSt/TiO₂ particles and the crystal structures of the AgCl doped TiO₂ hollow particles were characterized.The photocatalytic activity of the doped TiO₂ hollow particles in degradation of Rhodamine B was tested under UV and visible lights and compared to that with Ag doped TiO₂ particles.The results showed that TiO₂ hollow particles,either doped with Ag or AgCl,demonstrated higher photocatalytic activity than the pure TiO₂ particles.This enhancement in photocatalytic activity was more significant with AgCl doped TiO₂ than that with Ag doped,and more distinct when the degradation was done under visible light than that under LTV light.     

Keggin型铬取代的磷钨杂多阴离子/二氧化钛纳米膜光催化剂的制备及可见光催化性能

以钛酸四丁酯Ti(OC₄H₉)₄为TiO₂前驱体,Keggin型铬取代的杂多阴离子PW₁₁Cr为可见光活性组分,采用溶胶-凝胶提拉法在玻片表面制备了PW₁₁Cr/TiO₂纳米膜光催化剂,并用UV-Vis DRS、IR、XRD、SEM和TEM等技术手段对催化剂的光吸收性质、化学组成、晶相和表面结构形貌等进行了表征;讨论了膜中PW₁₁Cr和TiO₂相互作用的方式;以染料模型污染物RhB的可见光催化降解为探针,评估了PW₁₁Cr/TiO₂光催化剂的可见光催化活性,讨论了光催化反应机理,并与TiO₂的光催化反应机理进行了比较;考察了焙烧温度、PW₁₁Cr剂量和溶液pH值对光催化活性的影响;最后用RhB的循环降解实验评估了催化剂的光催化稳定性。 实验结果表明,PW₁₁Cr/TiO₂光催化剂对可见光有明显吸收,较低焙烧温度(100 ℃)下得到的膜为无定形结构,而较高焙烧温度(500 ℃)为纳晶结构;前者的光催化活性较高,在200 W金卤灯照射下降解10 μmol/L RhB,120 min的降解率为95%,4 h的COD去除率为72%;羟基自由基是导致RhB降解的主要氧活性物质;低的膜处理温度,高的PW₁₁Cr负载量和溶液酸性有利于提高PW₁₁Cr/TiO₂膜的光催化活性;经循环重复使用10次,PW₁₁Cr/TiO₂膜的光催化活性仅有较少损失。     

Preparation and investigation of structural and photocatalytic properties of phosphate modified titanium dioxide

A series of high surface area titanium dioxide samples (P-TiO₂) with varying phosphate content have been prepared by the sol–gel technique. The structural characterization of the samples included X-ray powder diffraction, diffuse reflectance infrared and UV–vis spectroscopy (DRIFT and UV–vis–DR), and nitrogen adsorption measurements. The structural properties of the P-TiO₂ samples significantly changed with the phosphate content and calcination temperature. According to XRD data the presence of phosphate shifts the anatase rutile phase transition to higher temperatures, revealing that phosphate improves the thermal stability of the samples. The specific surface area and the semiconductor band gap energy increase with the phosphate content.

The photocatalytic activity of TiO₂ and P-TiO₂ was studied by phenol degradation in liquid phase. A small amount of phosphate of the catalysts increases the photocatalytic activity, but further increase of the P/Ti molar ratio (above 0.01), leads to a considerable loss in activity. The optimal calcination temperature of P-TiO₂ was 300–500 °C. The phenol conversion rate is highest with catalysts calcined at 700 °C, but phenol does not degrade to carbon dioxide.     

共沉淀法制备Ag/AgCl-TiO2空心复合纳米微球及其光催化性能

通过甲基丙烯酸与苯乙烯聚合制备了表面负电性的聚苯乙烯(PSt)纳米乳胶粒. 在乙醇与水的混合溶剂中, 用硅烷偶联剂乙烯基三甲氧基硅烷对其进行表面改性后加入钛酸四丁酯、 氯化钠和硝酸银, 以PSt乳胶粒为模板采用共沉淀法制备了PSt-AgCl-TiO₂复合微球. 在180 ℃对其进行液相预处理及煅烧去除PSt模板后制备了Ag/AgCl-TiO₂空心复合粒子. 对各阶段产物的形貌、 晶体结构和比表面积等进行了表征. 结果表明, 所得产物为Ag/AgCl与锐钛矿型TiO₂复合的空心粒子, 其比表面远大于商品TiO₂(P25). 考察了Ag/AgCl-TiO₂复合粒子在紫外光与可见光下对罗丹明B(RhB)降解的催化活性. 结果表明, 在紫外光下n(Ag)/n(Ti)=0.1%的Ag/AgCl-TiO₂复合粒子活性最高, 30 min时对RhB的降解率比不含Ag/AgCl的TiO₂空心微球提高了13%; 虽然Ag/AgCl-TiO₂在可见光下的催化活性远比紫外光下低, 但与纯TiO₂空心纳米微球相比其催化活性仍明显增强. n(Ag)/n(Ti)=2.0%的Ag/AgCl-TiO₂复合粒子催化活性最高, 120 min时对RhB的降解率比不含Ag/AgCl的TiO₂空心微球提高了38%.     

Influence of the size of doping ion on phase stability and oxygen permeability of SrCo0.8Fe0.2O3−δ oxide

The compounds of SrCo_0.8Fe_0.2O_3−δ (SCF) doped with Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Ti⁴⁺ and Zr⁴⁺ are synthesized by conventional solid-state reaction. The phase stabilities and oxygen permeabilites of these synthesized oxides are investigated. It is found that the doping Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺ totally dissolve into the SCF unit cell, while SrTiO₃ and SrZrO₃ phases form when SCF is doped with Ti⁴⁺ and Zr⁴⁺, respectively. A possible mechanism of the doping behavior is proposed to interpret the structure transformation of the SCF unit cell. Phase stability increases directly with the size of the doping ion when SCF is doped with the ions in the same group. However, the influence of the size of the doping ion on the oxygen permeation behavior is negligible for the membranes doped with the ions in the same group.     

Thermal solid–solid interactions and physicochemical properties of NiO/Fe2O3 system doped with K2O

The effects of calcination temperature and doping with K₂O on solid–solid interactions and physicochemical properties of NiO/Fe₂O₃ system were investigated using TG, DTA and XRD techniques. The amounts of potassium, expressed as mol% K₂O were 0.62, 1.23, 2.44 and 4.26. The pure and variously doped mixed solids were thermally treated at 300, 500, 750, 900 and 1000 °C. The catalytic activity was determined for each solid in H₂O₂ decomposition reaction at 30–50 °C. The results obtained showed that the doping process much affected the degree of crystallinity of both NiO and Fe₂O₃ phases detected for all solids calcined at 300 and 500 °C. Fe₂O₃ interacted readily with NiO at temperature starting from 700 °C producing crystalline NiFe₂O₄ phase. The degree of reaction propagation increased with increasing calcination temperature. The completion of this reaction required a prolonged heating at temperature >900 °C. K₂O-doping stimulates the ferrite formation to an extent proportional to its amount added. The stimulation effect of potassium was evidenced by following up the change in the peak height of certain diffraction lines characteristic NiO, Fe₂O₃, NiFe₂O₄ phases located at “d” spacing 2.08, 2.69 and 2.95 Å, respectively. The change of peak height of the diffraction lines at 2.95 Å as a function of firing temperature of pure and doped mixed solids enabled the calculation of the activation energy (ΔE) of the ferrite formation. The computed ΔE values were 120, 80, 49, 36 and 25 kJ mol⁻¹ for pure and variously doped solids, respectively. The decrease in ΔE value of NiFe₂O₄ formation as a function of dopant added was not only attributed to an effective increase in the mobility of reacting cations but also to the formation of potassium ferrite. The calcination temperature and doping with K₂O much affected the catalytic activity of the system under investigation.