Synthesis,Characterization, and Photocatalytic Properties of Ag/TiO2 Composite Nanofibers Prepared by Electrospinning

Ag nanoparticles (Ag NPs) embedded titanium dioxide (TiO₂) nanofibers were fabricated by colloidal sol process, electrospinning, and calcination technique. Calcination of the electrospun nanofibers were heat treated at 600°C for 180 minutes in air atmosphere. X-ray diffraction patterns exhibited that the anatase phase and silver coexisted in the resulted Ag NPs/TiO₂ nanofibers; transmission electron microscopy demonstrated Ag NPs well spread in the porous microstructure of composite fibers. The prepared nanofibers were utilized as photocatalyst for degradation of methyl orange. The degradation rate of methyl orange dye solution containing Ag/TiO₂ composite nanofibers is 99% only after irradiation for 3 hours. It is proposed that these new Ag NPs/TiO₂ composite nanofibers will have potential application in water pollution treatment.      

TiO2纳米纤维无纺布的制备及光催化性能研究

以聚乙烯吡咯烷酮(PVP)作为配位剂与钛酸正丁酯(Ti(C₄H₉O)₄)反应制得前驱体，再以乙醇为溶剂，CH3COOH作为催化剂，采用静电纺丝法制得PVP/TiO₂复合纳米纤维，经550 ℃、700 ℃和900 ℃焙烧后分别得到以锐钛矿型的TiO₂为主、以金红石型TiO₂为主和完全金红石晶型的TiO₂纳米纤维。对所制得的纳米纤维的结晶度、纯度和形貌，分别采用差热-热重分析(TG-DTA)、红外光谱(IR)、X射线粉末衍射(XRD)、扫描电镜(SEM)等进行了表征。光降解苯酚水溶液的实验结果表明，550 ℃下煅烧得到的以锐钛矿占主体的TiO₂纳米纤维，2 h使浓度为50 mg·L^-1苯酚水溶液的降解率超过85%，这充分说明这种TiO₂电纺纳米纤维具有良好的光催化性能。     

The Preparation and Characterization of La Doped TiO2 Nanotubes and Their Photocatalytic Activity

La-doped TiO₂ nanotubes (La/TiO₂ NTs) were prepared by the combination of sol-gel process with hydrothermal treatment. The prepared samples were characterized by using transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectra, and ultraviolet-visible spectra. The photocatalytic performance of La/TiO₂ NTs was studied by testing the degradation rate of methyl orange under ultraviolet (UV) irradiation. The results indicated La/TiO₂ NTs calcined at 300°C consisted of anatase as the unique phase. The absorption spectra of the La/TiO₂ NTs showed a stronger absorption in the UV range and a slight red shift in the band gap transition than that of pure TiO₂ nanotubes. The photocatalytic performance of TiO₂ NTs could be improved by the doping of lanthanum ions, which is ascribed to several beneficial effects the formation of Ti-O-La bond and charge imbalance, existing of oxygen defects and Ti³⁺ species, stronger absorption in the UV range and a slight red shift in the band gap transition, as well as higher equilibrium dark adsorption of methyl orange. 0.75 wt% La/TiO₂ NTs had the best catalytic activity.     

脉冲沉积制备Cu2O/TiO2纳米管异质结的可见光光催化性能

在用阳极氧化法制备有序排列TiO₂纳米管阵列薄膜的基础上,引入脉冲沉积工艺,成功实现了均匀、弥散分布的Cu₂O纳米颗粒修饰改性TiO₂纳米管阵列,形成Cu₂O/TiO₂ 纳米管异质结复合材料. 利用场发射扫描电镜（FESEM）、场发射透射电镜（FETEM）、X射线衍射（XRD）、X射线光电子能谱（XPS）和紫外-可见漫反射光谱（UV-Vis DRS）对样品进行表征,重点研究了Cu₂O/TiO₂ 纳米管异质结的光电化学特性和对甲基橙（MO）的可见光催化降解性能. 结果表明,Cu₂O纳米颗粒均匀附着在TiO₂纳米管阵列的管口和中部位置,所制备的Cu₂O/TiO₂ 纳米管异质结具有高效的可见光光催化性能;在浓度为0.01 mol·L^-1的CuSO₄溶液中制得的Cu₂O/TiO₂纳米管异质结表现出最好的电化学特性和光催化性能;另外,对Cu₂O纳米颗粒影响光催化活性的机理进行了讨论.     

In Situ ATR-FTIR and UV-Visible Spectroscopy Study of Photocatalytic Oxidation of Ethanol over TiO2 Nanotubes

The photocatalytic oxidation of ethanol over TiO₂ nanotubes (NTs) was investigated by in situ attenuated total reflection using Fourier transform infrared spectroscopy (ATR-FTIR) and ultraviolet (UV)-visible spectroscopy. In the ATR-FTIR study, the TiO₂ NTs were spread in a ZnSe crystal trough that was used as the reactor. The evolution of the reaction under UV irradiation was investigated by in situ monitoring of changes in the species at the surface of the TiO₂ NTs. Ethanol adsorbed on the TiO₂ NTs surface, forming alkoxide and hydroxide groups, which were then attacked by ^?OH, with the formation of a vinyl alcohol intermediate that was finally transformed to acetic acid. In addition, the species changes in the reaction solution were also investigated by in situ UV-visible spectroscopy using a small volume flow-through cell. The UV-visible data further confirmed the oxidation mechanism of ethanol on TiO₂ NTs elucidated by ATR-FTIR data.     

阳极氧化法制备TiO2纳米管及其光催化性能

纳米TiO₂对诸多环境污染物有显著的光催化降解作用,光催化已发展成为新型环境污染治理技术。本文采用阳极氧化法制备出TiO₂纳米管,对比了四种电解液组成(A氟化铵+硫酸铵+水;B氟化铵+硫酸铵+乙酸+水;C氟化铵+硫酸铵+甘油+水;D氢氟酸+二甲基亚砜(DMOS)+乙醇)对催化剂表面形貌及光催化性能的影响。结果表明,电解液A和C都制备出了形貌清晰的TiO₂纳米管,管径约为60~74 nm。样品经400 ℃煅烧,TiO₂晶型主要为锐钛矿相;经500 ℃煅烧,出现少量金红石相;经700 ℃煅烧,晶型全部为金红石相。具有良好形貌的TiO₂纳米管同时具有良好的紫外光吸收能力。当亚甲基蓝初始浓度为10 mg·L^-1,经500 ℃煅烧的TiO₂纳米管光催化活性最佳,光照30 min亚甲基蓝的降解率达89.98%。亚甲基蓝光催化降解反应符合一级反应动力学,反应速率常数为0.079 30。     

光驱动多孔无定形TiO2的形成机制与光催化性能的研究

以钛酸正丁醇和乙二醇为原料,采用溶剂热法合成了钛乙二醇盐(TG)前躯体,在高压汞灯照射下制备出无定形TiO2。利用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)、紫外-可见吸收光谱(UV-Vis)、表面光电压谱(SPS)、N2吸附-脱附对所得材料进行了结构和性能的表征。借助X射线吸收精细结构(XAFS)对无定形TiO2的形成机制进行了分析,并通过硝基苯的还原反应考察了材料的光催化性能。结果表明:在紫外光驱动无定形TiO2的形成过程中,中心元素Ti4+的配位环境发生变化,由八面体结构转变为四面体结构;由于特殊的孔道结构使得多孔无定形TiO2显示出较好的光催化活性。     

Enhancement of Visible-Light Photocatalytic Degradation of Tetracycline by Co-Doped TiO2 Templated by Waste Tobacco Stem Silk

In this study, Co-doped TiO₂ was synthesized using waste tobacco stem silk (TSS) as a template via a one-pot impregnation method. These samples were characterized using various physicochemical techniques such as N₂ adsorption/desorption analysis, diffuse reflectance UV–visible spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and electron paramagnetic resonance spectroscopy. The synthesized material was used for the photodegradation of tetracycline hydrochloride (TCH) under visible light (420–800 nm). No strong photodegradation activity was observed for mesoporous TiO₂ synthesized using waste TSS as a template, mesoporous Co-doped TiO₂, or TiO₂. In contrast, Co-doped mesoporous TiO₂ synthesized using waste TSS as a template exhibited significant photocatalytic degradation, with 86% removal of TCH. Moreover, owing to the unique chemical structure of Ti-O-Co, the energy gap of TiO₂ decreased. The edge of the absorption band was redshifted, such that the photoexcitation energy for generating electron–hole pairs decreased. The electron–hole separation efficiency improved, rendering the microstructured biotemplated TiO₂ a much more efficient catalyst for the visible-light degradation of TCH.     

Deposition of Hybrid Photocatalytic Layers for Air Purification Using Commercial TiO2 Powders

Photocatalytic nanomaterials, using only light as the source of excitation, have been developed for the breakdown of volatile organic compounds (VOCs) in air for a long time. It is a tough challenge to immobilize these powder photocatalysts and prevent their entrainment with the gas stream. Conventional methods for making stable films typically require expensive deposition equipment and only allow the deposition of very thin layers with limited photocatalytic performance. The present work presents an alternative approach, using the combination of commercially available photocatalytic nanopowders and a polymer or inorganic sol–gel-based matrix. Analysis of the photocatalytic degradation of ethanol was studied for these layers on metallic substrates, proving a difference in photocatalytic activity for different types of stable layers. The sol–gel-based TiO2 layers showed an improved photocatalytic activity of the nanomaterials compared with the polymer TiO2 layers. In addition, the used preparation methods require only a limited amount of photocatalyst, little equipment, and allow easy upscaling.     

Patterning Effect of a Sol-Gel TiO2 Overlayer on the Photocatalytic Activity of a TiO2/SnO2 Bilayer-Type Photocatalyst

TiO₂ films with a thickness of 75 ± 5 nm (anatase) were formed on SnO₂-film (580 ± 80 nm) coated soda-lime glass substrates (SnO₂/SL-glass) by a sol-gel method. Although the photocatalytic activity for CH₃CHO oxidation (_ex > 300 nm) significantly exceeded that of a standard TiO₂/quartz sample, it decayed with illumination time (t) at t > 0.75 h. Stripes of anatase TiO₂ films of 40 nm in thickness and 1 mm in width were prepared on the SnO₂/SL-glass substrate in a 1-mm pitch by photolysis of an organically modified sol-gel film. The TiO₂ patterning further increased the photocatalytic activity by a factor of 4.1 as compared to the non-patterned sample, and it was also maintained at 0 < t < 2 h. The flat band potentials of the TiO₂ and SnO₂ films are determined to be –0.34 and +0.07 V (vs. SHE), respectively, at pH = 7 by the Mott-Schottky plots. On the basis of the results, the outstanding patterning effects could be rationalized in terms of the vectorial charge separation at the interface between TiO₂ and SnO₂.     

卟啉锡敏化TiO_2纳米管的光催化活性和光电性能

制备了反-二羟基-5,10,15,10-四苯基卟啉锡敏化的TiO2纳米管,并以对硝基苯酚为模型污染物,对其在可见光照射下的光催化活性进行了研究。同时,将卟啉锡敏化的TiO2纳米粒子作为参照物,探讨了形貌对催化剂光催化活性的影响。实验结果表明,卟啉锡的引入可以明显地增强TiO2纳米管的可见光催化活性。与TiO2纳米粒子相比,卟啉锡对TiO2纳米管的敏化作用更加显著,表明催化剂的形貌在光催化过程中具有重要作用。此外,我们还考察了卟啉锡敏化的TiO2纳米管的光电化学行为,并与其光催化活性相关联。最后,对卟啉锡的敏化机理进行了初步的探讨。     

卟啉锡敏化TiO2纳米管的光催化活性和光电性能

制备了反-二羟基-5,10,15,10-四苯基卟啉锡敏化的TiO₂纳米管,并以对硝基苯酚为模型污染物,对其在可见光照射下的光催化活性进行了研究。同时,将卟啉锡敏化的TiO₂纳米粒子作为参照物,探讨了形貌对催化剂光催化活性的影响。实验结果表明,卟啉锡的引入可以明显地增强TiO₂纳米管的可见光催化活性。与TiO₂纳米粒子相比,卟啉锡对TiO₂纳米管的敏化作用更加显著,表明催化剂的形貌在光催化过程中具有重要作用。此外,我们还考察了卟啉锡敏化的TiO₂纳米管的光电化学行为,并与其光催化活性相关联。最后,对卟啉锡的敏化机理进行了初步的探讨。     

微乳法制备纳米TiO2 /SiO2的结构及光催化研究

Nanosized TiO₂ and TiO₂/SiO₂ particles were prepared by hydrolysis of tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS) in the TX-100 reverse microemulsion. These particles were characterized by TG-DSC, XRD, FTIR, TEM，N₂ adsorption-desorption. Their photocatalytic activity was tested by degradation of methyl orange. The result shows that TiO₂/SiO₂ nanoparticles are with a monodispersed spherical phase and a uniform size distribution，and TiO₂ particles are dispersed on the surface of SiO₂. The band for Ti-O-Si vibration in FTIR was observed, the Ti-O-Si bond increased the stability of anatase TiO₂, suppressed the phase transformation of titania from anatase to rutile. And due to the addition of SiO₂, the average size of titania decreased from 38 nm in pure TiO₂ to 5 nm in TiO₂/SiO₂. It was found, under UV light irradiation, TiO₂/SiO₂ particles showed higher activity than pure TiO₂, and TiO₂/SiO₂(1/1) particles showed the highest photocatalytic activity on the photocatalytic decomposition of methyl orange, which was influenced by crystal structure, particle size, crystallinity and Surface area Characteristics.     

控制胶体合成法制备掺铁TiO_2粉末及光催化降解甲基橙

分别采用控制胶体合成法和溶胶-凝胶法制备了2种不同掺铁方式的TiO2粉末,并用XRD、TEM、BET、UV-Vis、FS等技术对样品进行了表征。在紫外光照射下,以甲基橙溶液的光催化降解反应为探针,研究了掺Fe离子浓度、包覆的次数、不同掺杂方式对样品光催化活性的影响。结果表明,以均匀掺铁TiO2(铁含量大于0.02mol%)干凝胶粉末为载体,采用控制胶体合成法制备了具有P-N结型结构的非均匀掺铁TiO2粉末,其光催化活性较均匀掺杂TiO2粉末明显提高,并且随着包覆次数(≤3次)的增加而增强,以0.04mol%掺铁TiO2粉末包覆3次后制备的样品具有最佳光催化活性,其表观速率常数是未掺杂的TiO2粉末的5.32倍,是具有相同Fe含量的均匀掺杂TiO2粉末的4.58倍。     

Photocatalytic Oxidation of HMF under Solar Irradiation: Coupling of Microemulsion and Lyophilization to Obtain Innovative TiO2-Based Materials

The photocatalytic oxidation of biomass-derived building blocks such as 5-hydroxymethylfurfural (HMF) is a promising reaction for obtaining valuable chemicals and the efficient long-term storage of solar radiation. In this work, we developed innovative TiO₂-based materials capable of base-free HMF photo-oxidation in water using simulated solar irradiation. The materials were prepared by combining microemulsion and spray-freeze drying (SFD), resulting in highly porous systems with a large surface area. The effect of titania/silica composition and the presence of gold-copper alloy nanoparticles on the properties of materials as well as photocatalytic performance were evaluated. Among the lab-synthesized photocatalysts, Ti₁₅Si₈₅ SFD and Au₃Cu₁/Ti₁₅Si₈₅ SFD achieved the higher conversions, while the best selectivity was observed for Au₃Cu₁/Ti₁₅Si₈₅ SFD. The tests with radical scavengers for both TiO₂-m and Au₃Cu₁/Ti₁₅Si₈₅ SFD suggested that primary species responsible for the selective photo-oxidation of HMF are photo-generated electrons and/or superoxide radicals.     

Bi2WO6/TiO2纳米管异质结构复合材料的多模式下的光催化活性比较

以TiO₂纳米管为模板,采用多组分自组装结合水热法制备Bi₂WO₆/TiO₂纳米管异质结构复合材料。通过多种技术如X射线衍射（XRD）,X射线光电子能谱（XPS）,N₂吸附-脱附,扫描电镜（SEM）,高分辨透射电镜（HRTEM）和紫外可见漫反射吸收光谱（UV-Vis DRS）考察所制备样品的组成、结构、形貌、光吸收和电子性质。Bi₂WO₆纳米片或纳米粒子分布在TiO₂纳米管上,形成异质结构。随后,通过在紫外、可见和微波辅助光催化模式下降解染料罗丹明B（RhB）来评价复合催化剂的光催化活性。与TiO₂纳米管和Bi₂WO₆相比,Bi₂WO₆/TiO₂-35纳米管在多模式下表现出更优异的光催化活性。与紫外和可见降解模式相比,Bi₂WO₆/TiO₂-35纳米管在微波辅助光催化模式下对RhB的降解效率最高。这种增强的光催化活性源于适量Bi₂WO₆的引入、纳米管独特的形貌特征和降解模式所引起的增强的量子效率。降解过程中的活性物种被证明是h⁺,·OH和·O₂^-自由基。而且,在微波辅助光催化模式下,可产生更多的·OH和·O₂^-自由基。     

Bi2WO6/TiO2纳米管异质结构复合材料的多模式下的光催化活性比较

以TiO₂纳米管为模板,采用多组分自组装结合水热法制备Bi₂WO₆/TiO₂纳米管异质结构复合材料。通过多种技术如X射线衍射（XRD）,X射线光电子能谱（XPS）,N₂吸附脱附,扫描电镜（SEM）,高分辨透射电镜（HRTEM）和紫外可见漫反射吸收光谱（UV-Vis DRS）考察所制备样品的组成、结构、形貌、光吸收和电子性质。Bi₂WO₆纳米片或纳米粒子分布在TiO₂纳米管上,形成异质结构。随后,通过在紫外、可见和微波辅助光催化模式下降解染料罗丹明B（RhB）来评价复合催化剂的光催化活性。与TiO₂纳米管和Bi₂WO₆相比,Bi₂WO₆/TiO₂-35纳米管在多模式下表现出更优异的光催化活性。与紫外和可见降解模式相比,Bi₂WO₆/TiO₂-35纳米管在微波辅助光催化模式下对RhB的降解效率最高。这种增强的光催化活性源于适量Bi₂WO₆的引入、纳米管独特的形貌特征和降解模式所引起的增强的量子效率。降解过程中的活性物种被证明是h⁺,·OH和·O₂^-自由基。而且,在微波辅助光催化模式下,可产生更多的·OH和·O₂^-自由基。     

One-Pot Synthesis of Nitrogen-Doped TiO2 with Supported Copper Nanocrystalline for Photocatalytic Environment Purification under Household White LED Lamp

Developing efficient and cheap photocatalysts that are sensitive to indoor light is promising for the practical application of photocatalysis technology. Here, N-doped TiO₂ photocatalyst with loaded Cu crystalline cocatalyst is synthesized by a simple one-pot method. The structure is confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy analysis, which exhibit that Cu metal nanocrystalline is uniformly deposited on the surface of N-doped TiO₂ material. UV-Vis absorption spectra illustrate that the modified samples possess favorable visible light absorption properties and suppressed-electron hole separation. The as-fabricated Cu-loaded N-TiO₂ materials show high activity in photocatalytic decomposing isopropanol and inactivating E. coli under the irradiation of a household white LED lamp. The developed synthetic strategy and photocatalytic materials reported here are promising for indoor environment purification.     

TiO_2纳米管双室光电化学池光催化制氢的研究

以阳极氧化法在纯钛表面制备了高度有序的Ti O2纳米管阵列,并通过SEM观察其表面形貌。采用双室光电化学池制氢体系,利用太阳光照Ti O2产生的光电压与双室电解液p H差产生的化学偏压的协同效应,不施加外加电压,可直接在阴极室还原制取氢气。通过在碱性电解液中添加乙二醇为电子给体,将光解水制氢与有机物的降解耦合为一体,提高太阳能的利用率,同时考察了阳极室电解液中添加不同含量乙二醇对Ti O2纳米管光阳级的光电化学性能及产氢量的影响。实验结果表明,乙二醇的添加降低了光生电子-空穴对的复合几率,使Ti O2纳米管的光电流、光电压、产氢量得到显著提高。当添加乙二醇的浓度为10vol%时光电流达到13.7 m A·cm-2,无外加电压条件下,双室光电化学池中的产氢速率最高达到3.8μmol·min-1·cm-2。     

TiO2纳米管双室光电化学池光催化制氢的研究

以阳极氧化法在纯钛表面制备了高度有序的TiO₂纳米管阵列,并通过SEM观察其表面形貌。采用双室光电化学池制氢体系,利用太阳光照TiO₂产生的光电压与双室电解液pH差产生的化学偏压的协同效应,不施加外加电压,可直接在阴极室还原制取氢气。通过在碱性电解液中添加乙二醇为电子给体,将光解水制氢与有机物的降解耦合为一体,提高太阳能的利用率,同时考察了阳极室电解液中添加不同含量乙二醇对TiO₂纳米管光阳级的光电化学性能及产氢量的影响。实验结果表明,乙二醇的添加降低了光生电子-空穴对的复合几率,使TiO₂纳米管的光电流、光电压、产氢量得到显著提高。当添加乙二醇的浓度为10vol%时光电流达到13.7mA·cm^-2,无外加电压条件下,双室光电化学池中的产氢速率最高达到3.8μmol·min^-1·cm^-2。