硫和银共掺杂介孔TiO2的制备、表征及其对染料的光催化降解活性

以P123为模板,以钛酸四正丁酯、硝酸银和硫脲为原料采用模板法制备了一系列硫和银共掺杂介孔TiO₂光催化材料．利用SEM、XRD、BET和紫外-可见光谱等技术对其形貌、晶体结构及表面结构、光吸收特性等进行了表征．以甲基橙溶液的光催化降解为模型反应,考察了不同掺杂量的样品在紫外和可见光下的光催化性能．结果表明,用模板法制备的共掺杂介孔TiO₂光催化材料在紫外和可见光条件下较纯介孔TiO₂和单掺杂介孔TiO₂对甲基橙溶液具有更好的光催化降解效果, 且硫和银的掺杂量及样品焙烧温度显著影响该材料的催化性能．当硫掺杂量为2mol%和银掺杂量为1mol%,在500 oC 焙烧2 h所得光催化材料的催化性能最佳,4 h即可使甲基橙的降解率达98.8%,重复使用4次仍可使甲基橙的降解率保持在87.5%以上     

铈和磷钨酸共掺杂纳米二氧化钛中空纤维的制备及其光催化活性

以棉花纤维为模板,以钛酸四正丁酯、硝酸铈铵和磷钨酸为原料采用模板法制备了一系列铈和磷钨酸共掺杂的、具有中空纤维结构的TiO₂光催化材料, 利用扫描电子显微镜、X射线衍射、BET和紫外-可见光谱等技术对其形貌、晶体结构及表面结构、光吸收特性等进行了表征. 以苯酚溶液的光催化降解为模型反应,考察了不同掺杂量的样品在紫外和可见光下的光催化性能. 结果表明,用模板法制备的TiO₂纤维材料具有中空结构,共掺杂的TiO₂纤维在紫外和可见光条件下较纯TiO₂纤维和单掺杂TiO₂纤维对苯酚溶液具有更好的光催化降解效果, 且铈和磷钨酸的掺杂量显著影响该纤维材料的催化性能;当铈掺杂量为0.3mol%和磷钨酸掺杂量为2mol%,在500 oC焙烧2 h所得中空纤维材料的催化性能最佳,4 h即可使苯酚溶液的降解率达98.5%;重复使用4次仍可使苯酚溶液的降解率保持在87%以上,且该催化剂材料易于离心分离去除.     

镧掺杂介孔TiO2光催化剂的制备、表征及其光催化性能

以钛酸四正丁酯和硝酸镧为原料, 以P123为模板剂,采用模板法合成了La掺杂型介孔TiO₂光催化剂, 借助TGA-DSC、BET、XRD及UV-Vis等测试手段对样品进行了表征,并以苯酚为模型污染物考察了镧掺杂量对样品光催化活性的影响．结果表明: La掺杂介孔TiO₂光催化剂孔径分布较均匀(～10 nm),比表面积可达165 m²/g．与纯介孔TiO₂相比,经掺杂改性后的样品在紫外光区及可见光区的吸收显著增强,对光具有更高的利用率,La掺杂可显著提高介孔TiO₂的光催化活性.     

高比表面积TiO2与g-C3N4复合材料的光催化性能及机理研究

本文通过简单的溶剂热法制备了g-C₃N₄与高比表面积的TiO₂复合材料,该方法操作简单且能耗低. 甲基橙降解实验结果表明,高比表面积的TiO₂有效提高了光催化活性. 光电化学测试结果表明,与g-C₃N₄复合后,TiO₂的电荷载流子迁移速率得到明显改善. g-C₃N₄/高比表面积-TiO₂的光催化活性很强,在100分钟内,6%-g-C₃N₄/高比表面积-TiO₂对甲基橙的降解程度可达92.44%. 6%-g-C₃N₄/高比表面积-TiO₂不仅具有良好的光催化降解性能,还具有较高的稳定性. 本文对6%-g-C₃N₄/高比表面积-TiO₂的光催化机理也进行了系统的研究.     

氮掺杂TiO2的冲击合成及可见光催化活性研究

 冲击相变及冲击诱导化学反应可导致材料的物理、化学性能发生显著改变。采用炸药爆轰驱动飞片高速碰撞产生冲击波的方法,对富氮掺杂物双氰胺（C₂N₄H₄）与P25 TiO₂或偏钛酸（H₂TiO₃）的粉末混合物进行冲击加载,对回收产物进行X射线粉末衍射、透射电子显微镜、X光电子能谱、比表面积及紫外-可见漫反射光谱表征,通过亚甲基蓝和罗丹明B评价了回收产物的可见光催化降解活性。结果表明：以P25 TiO₂为原料的冲击氮掺杂浓度可达8.88%,掺杂样品具有明显的可见光吸收,能带宽度减小到1.75 eV,样品中形成了少量Srilankite高压相;而以偏钛酸为原料的冲击氮掺杂浓度为3%～4%,能带宽度变化较小,但是由于其独特的冲击脱水膨胀机理,比表面积剧增。冲击氮掺杂样品对亚甲基蓝和罗丹明B染料有较好的吸附和可见光催化降解作用,其中高飞片速度处理的样品有更高的光催化降解活性。     

FeTPP-Cr-TiO2微球的制备及其可见光催化性能

通过四苯基铁卟啉敏化Cr掺杂TiO₂微球成功合成了一种复合改性可见光催化剂FeTPP-Cr-TiO₂.利用XRD、FT-IR、SEM、XPS、UV-Vis和N₂吸附-脱附等温线等技术对其结构和形貌进行了表征.以亚甲基蓝为目标降解物,在150 W氙灯的辐照下,考察了其可见光催化活性.结果表明FeTPP-Cr-TiO₂呈锐钛矿相,表面积为74.7 m²/g.与Cr-TiO₂和FeTPP-TiO₂相比,FeTPP-Cr-TiO₂表现出很好的可见光降解性能.以三种喹诺酮类抗生素（洛美沙星、诺氟沙星和氧氟沙星）为实验对象,考察了FeTPP-Cr-TiO₂降解水体中抗生素的可行性,对三种抗生素均有很高的降解率,降解过程符合一级动力学模型,反应动力学常数分别为3.02×10^-2、2.81×10^-2和3.86×10^-2min^-1,半衰期为22.9、24.6及17.9 min.     

镧掺杂对锐钛矿TiO2电子结构与光催化活性影响的第一性原理研究

基于DFT+U方法,对镧掺杂锐钛矿TiO₂及其氧空缺的稳定性以及对电子结构、光催化性质的性质进行了第一性原理研究．计算结果表明掺杂浓度和位置对结构稳定性的影响机制符合鲍林规则;结合晶体场理论和结构形变以及态密度的分析发现镧掺杂对带隙的调制不是通过掺杂带的引入,而是由结构形变决定．吸收光谱的模拟结果显示通过镧掺杂会提高可见光的吸收效率,和实验结果吻合．对氧空缺的后续研究表明氧空缺的存在会增强镧掺杂锐钛矿TiO₂的稳定性,提高其光催化活性．     

Photocatalytic Activity of N-doped TiO2 Photocatalysts Prepared from the Molecular Precursor (NH4)2TiO(C2O4)2

用不同温度控制分解草酸氧钛铵制备N掺杂TiO₂光催化剂．利用XRD、IR、热分析、N₂吸-脱附等温线、XPS、紫外可见漫反射光谱和SEM表征了N-TiO₂光催化剂的结构．400～600 oC焙烧的N-TiO₂光催化剂为纯锐钛矿相,而700 oC焙烧的N-TiO₂光催化剂为锐钛矿和金红石混合相．N掺杂在TiO₂的间隙位使锐钛矿相TiO₂带隙变窄．在光降解甲基橙的反应中,600和400 oC焙烧的N-TiO₂催化剂分别在紫外光和全波长光照射下有最好活性;700 oC焙烧的N-TiO₂催化剂无论在紫外光和全波长光下都表现出最好的比活性,即最高的光量子效率,这可以归因于700 oC焙烧的N-TiO₂光催化剂良好的结晶程度和锐钛矿-金红石异相结的存在．     

Ag-Cu纳米颗粒修饰的N掺杂TiO2纳米棒阵列及其高效光催化CO2还原应用

本文采用微纳加工方法制备了负载高密度Ag-Cu纳米颗粒的N掺杂TiO₂纳米棒阵列样品. 通过TiO₂的N掺杂,可将其吸光范围调控至与Ag纳米颗粒的等离激元吸收频率相匹配的波段,从而实现复合材料中肖特基结与共振能量转移过程的协同作用. 与此同时,Cu纳米颗粒可以为CO₂还原提供活性位点. 在全谱光照射下,复合样品光催化CO₂还原的活性显著提高,CH₄生成速率可达720 μmol·g^-1·h^-1.     

Visible-Light Activities of Erbium Doped BiVO4 Photocatalysts

采用水热合成法,制备出Er掺杂的BiVO₄复合光催化剂,并采用XRD、SEM、XPS和紫外-可见漫反射光谱技术对其进行分析表征．通过可见光下降解水溶液中甲基橙分子来考察其光催化性能,结果显示掺杂组份以氧化物Er₂O₃形式存在于的复合光催化剂中;且掺杂复合光催化剂的可见光吸收和催化活性都比纯BiVO₄有所增强．     

Enhanced photocatalytic activity and stability of nano-scaled TiO2 co-doped with N and Fe

Titanium dioxide (TiO₂) nanoparticles co-doped with N and Fe were prepared via modified sol-gel process. The products were characterized by transmission electron microscopy (TEM), N₂ adsorption, X-ray diffraction (XRD), Raman spectroscopy, UV-vis spectroscopy, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS). It is shown that the prepared TiO₂ particles were less than 10 nm with narrow particle size distribution. The addition of MCM-41 caused the formation of Ti-O-Si bond which fixed the TiO₂ on MCM-41 surface, thus restricted the agglomeration and growth of TiO₂ particles. The photocatalytic performance in the degradation of methylene blue showed that N, Fe co-doped TiO₂ exhibited much higher photocatalytic activity than doped sample with nitrogen or Fe³⁺ alone under both UV and visible light. N, Fe co-doping decreased the loss of doping N during the degradation reaction, thus increased the photocatalytic stability. It was also found that the nitridation time had significant influence on the photocatalytic activity of prepared TiO₂ catalysts.     

Preparation and characterization of TiO2 photocatalysts co-doped with iron (III) and lanthanum for the degradation of organic pollutants

Titanium dioxide photocatalysts co-doped with iron (III) and lanthanum were prepared by a facile sol-gel method. The structure of catalysts was characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the samples were evaluated by the degradation of methylene blue in aqueous solutions under visible light (λ > 420 nm) and UV light irradiation. Doping with Fe³⁺ results in a lower anatase to rutile (A-R) phase transformation temperature for TiO₂ particles, while doping with La³⁺ inhibits the A-R phase transformation, and co-doping samples indicate that Fe³⁺ partly counteracts the effect of La³⁺ on the A-R transformation property of TiO₂. Fe-TiO₂ has a long tail extending up the absorption edges to 600 nm, whereas La-TiO₂ results in a red shift of the absorption. However, Fe and La have synergistic effect in the absorption of TiO₂. Compared with Fe³⁺ and La³⁺ singly doped TiO₂, the co-doped simple exhibits excellent visible light and UV light activity and the synergistic effect of Fe³⁺ and La³⁺ is responsible for improving the photocatalytic activity.     

Quenching of spin-spin relaxation in Fe(NO3)3·9H2O single crystals by application of a magnetic field

The ferric ions in Fe(NO₃)₃·9H₂O are connected in pairs by a screw dyad axis. When a magnetic field is applied, two neighbouring ions may have different energy splittings unless the field is applied parallel or perpendicular to the screw dyad axis. As a flip-flop process on the whole must be energy conserving, the spin-spin relaxation time depends on the angle between the field and the screw dyad axis. This effect is demonstrated by Mössbauer effect measurements on single crystals of Fe(NO₃)₃·9H₂O.     

Complexation between variable-valency uranium and organic ligands in solutions,their photostability and spectral identification

We discuss possible directions for searching for prospective materials based on low-valency uranium (III–V) as detection media for hard electromagnetic radiation. We have studied the processes of formation of tetravalent and pentavalent uranium complexes from UO₂(NO₃)₃·6H₂O and UO₂Cl₂·H₂O in DMF and with addition of CCl₄, including when the systems are exposed to radiation in the visible range (400–450 nm). In the first case (UO₂(NO₃)₃·6H₂O solutions in DMF), upon irradiation we observe stable complexes of pentavalent uranium, and when CCl₄ is added to the solution we observe complexes of tetravalent uranium. In the system UO₂Cl₂·3H₂O in DMF, we do not observe the appearance of new forms of uranium; but when CCl₄ is added, then complexes of tetravalent uranium are formed. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 184–187, March–April, 2007.     

Structure and lithium storage performances of nickel hydroxides synthesized with different nickel salts

Nickel hydroxides with hierarchical micro-nano structures are prepared by a facile homogeneous precipitation method with different nickel salts (Ni(NO₃)₂·6H₂O, NiCl₂·6H₂O, and NiSO₄·6H₂O) as raw materials. The effect of nickel sources on the microstructure and lithium storage performance of the nickel hydroxides is studied. It is found that all the three prepared samples are α-nickel hydroxide. The nickel hydroxides synthesized with Ni(NO₃)₂·6H₂ or NiCl₂·6H₂O show a similar particle size of 20–30 μm and are composed of very thin nano-sheets, while the nickel hydroxide synthesized with Ni(SO₄)₂·6H₂O shows a larger particle size (30–50 μm) and consists of very thin nano-walls. When applied as anode materials for lithium-ion batteries (LIBs), the nickel hydroxide synthesized with NiSO₄·6H₂O exhibits the highest discharge capacity, but its cyclic stability is very poor. The nickel hydroxides synthesized with NiCl₂·6H₂O exhibit higher discharge capacity than the nickel hydroxides synthesized with Ni(NO₃)₂·6H₂O, and both of them show much improved cyclic stability and rate capability as compared to the nickel hydroxide synthesized with Ni(SO₄)₂·6H₂O. Moreover, pseudocapacitive behavior makes a great contribution to the electrochemical energy storage of the three samples. The discrepancies of lithium storage performance of the three samples are analyzed by ex-situ XRD, FT-IR, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) tests.     

Preparation of Zn2+–Ni2+–Fe3+–CO32−LDHs and study of photocatalytic activities for decomposition of Methyl Orange solution

New type photocatalytic materials of Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs were prepared by complexing agent-assisted homogeneous precipitation technique and Zn(NO₃)₂·6H₂O, Ni(NO₃)·6H₂O, Fe(NO₃)₃·9H₂O used as raw materials in the case of molar ratio of Zn²⁺/Ni²⁺/Fe³⁺ = 1:6:2. Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs having a specific surface area of 96.5 m²/g. The structure and catalytic properties of the material were systematically studied. The experimental results show that the Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs has a higher adsorption performance and lower band gap which make it an excellent catalyst for reducing the degradation of the methyl orange. Study on the process of photocatalytic reaction shows that Methyl Orange was adsorbed to the layer of Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs, and then it was photodecomposed to inorganic molecules and ions by Zn²⁺, Ni²⁺, and Fe³⁺ on the surface of Zn²⁺–Ni²⁺–Fe³⁺–CO₃^2?LDHs.     

N,Fe, La三掺杂锐钛矿型TiO2能带调节的理论与实验研究

采用基于密度泛函理论(DFT)的平面波超软赝势方法(PWPP), 利用Material studio 计算N, Fe, La三种元素掺杂引起的锐钛矿TiO₂晶体结构、能带结构和态密度变化. 并通过溶胶-凝胶法制得锐钛矿型本征TiO₂, N, Fe共掺杂TiO₂和N, Fe, La共掺杂TiO₂; 用X射线衍射和扫描电镜表征结构; 紫外-可见分光光度计检测TiO₂对甲基橙的降解效率变化. 计算结果表明, 由于N, Fe, La三掺杂TiO₂的晶格体积、键长等发生变化, 导致晶体对称性下降, 光生电子-空穴对有效分离, 同时在导带底和价带顶形成杂质能级, TiO₂禁带宽度由1.78 eV变为1.35 eV, 减小25%, 光吸收带边红移, 态密度数增加, 电子跃迁概率提升, 光催化能力增加. 实验结果表明: 离子掺杂使颗粒变小, 粒径大小: 本征TiO₂>N/Fe_TiO₂>N/Fe/La_TiO₂, 并测得N/Fe/La_TiO₂发光峰425 nm, 能隙减小, 光催化能力比N/Fe_TiO₂强, 增强原因是杂质能级和电子态数量增加引起.