聚苯乙烯/纳米TiO_2/硅藻土复合材料的制备及其性能研究

通过溶胶-凝胶法成功制备了纳米TiO_2/硅藻土复合材料,并通过浸渍法进一步制备了聚苯乙烯/TiO_2/硅藻土复合材料。采用扫描电子显微镜、X射线粉末衍射、傅里叶红外光谱和紫外-可见分光光度计等手段对样品进行表征,分析了复合材料的形貌、结构、组成及其光催化降解甲醛的性能。结果表明:硅藻土负载的纳米TiO_2具有良好的光催化性能,聚苯乙烯包覆可以提高纳米TiO_2/硅藻土复合材料的分散性和稳定性,对甲醛的光催化降解能力并无大的影响。其中0.1%聚苯乙烯包覆复合材料的光催化效果最好,在溶液中甲醛降解率可以达到47.08%,在空气中可以达到54.96%。     

TiO_2/氧化石墨烯复合纳米管的制备与光催化性能

采用水热法制备了TiO_2/氧化石墨烯(GO)系列复合纳米管光催化剂,分别利用X射线衍射(XRD)、透射电子显微镜(TEM)、拉曼光谱和紫外可见(UV-Vis)漫反射光谱对样品进行表征,并通过降解亚甲基蓝实验评估了样品的光催化性能。XRD与TEM表征结果表明,样品为锐钛矿相的纳米管结构,拉曼光谱结果进一步证实了其晶相,且观察到显著的GO拉曼峰。GO引入后,样品的吸收边未见显著移动,而在可见光区域出现GO所贡献的吸收增强。光催化活性表征结果显示,TiO_2纳米管的光催化活性明显强于纳米颗粒;GO引入后,随着GO量的增加,复合纳米管的光催化活性呈现先增强后减弱的变化趋势,GO溶液用量为2mL的样品表现出最佳的光催化性能。我们还对系列TiO_2/GO复合纳米管样品的光催化性能变化机制作出了详细讨论。     

Pt纳米颗粒负载SrTiO3/TiO2异质结结构制备及制氢性能

本文以固定n(Sr)/n(Ti)摩尔比0.4的SrTiO_3/TiO_2(金红石相)异质结纳米颗粒,通过"光催化还原沉积方法"制备不同质量分数的纳米铂颗粒(0、1%、2%、5%),探究其催化活性的变化,采用XRD、SEM、UV-vis、XPS方法对其进行表征,并做了相关光催化分解水产氢性能测试.结果表明:负载贵金属Pt纳米颗粒量越大,对应的Pt晶粒平均尺寸为40.8 nm,1%Pt纳米颗粒SrTiO_3/TiO_2异质结构的BET比表面积在23.195 m~2/g处最高,并且介孔材料的特征是平均Barrett-Joyner-Halenda(BJH)孔径为13.60 nm,总孔体积为0.079 cm~3/g;高BET表面积和大的总孔体积强烈地支持SrTiO_3/TiO_2具有介孔结构的事实;相应的催化剂催化活性越高,其中负载5%Pt纳米颗粒的SrTiO_3/TiO_2纳米颗粒光催化8 h产氢量为3.574 mmol,平均产氢效率为0.447 mmol/(gcat·h),但从性价比的角度来考虑,其催化效率远不及负载1%Pt纳米颗粒的SrTiO_3/TiO_2纳米颗粒催化效率的5倍,因此负载5%Pt的SrTiO_3/TiO_2纳米颗粒光催化效率最高.     

CuMnO2/TiO2复合光催化剂增效催化降解亚甲基蓝

首次利用旋涂法将CuMnO_2纳米晶负载于TiO_2纳米棒阵列薄膜上,制备出光催化性能增强的CuMnO_2/TiO_2复合光催化剂,并考察了样品对亚甲基蓝(MB)的光催化降解性能。研究结果表明,CuMnO_2纳米晶和TiO_2纳米棒之间形成p-n异质结结构,能够有效促进电子和空穴的分离,使得CuMnO_2/TiO_2复合光催化剂具有更高的光催化性能。采用浓度为0.25 g/L的CuMnO_2悬浮液制得的CuMnO_2/TiO_2复合材料的光催化降解效率最高,其光催化效率和表观速率分别为88%和0.298 6 h~(-1),较纯TiO_2提高约26%和80%。     

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。     

不同温度下ZnO/ZnSe复合结构的制备及光催化性能

以氧化锌(ZnO)、硒粉(Se)以及硼氢化钠(NaBH4)为原料,采用浸渍覆膜法,在不同保温温度下(50,70和90℃),制备出具有核壳结构的ZnO/ZnSe纳米光催化材料。采用透射电子显微镜(TEM)、拉曼光谱(RAMAN)、紫外可见分光光度计(UV-Vis)、光催化性能测试等手段对其样品的结构、形貌以及光催化性能进行了表征。通过测试复合结构对一氧化氮(NO)的降解能力,评估其光催化效率。结果表明,样品的保温反应温度越高,附着在ZnO晶体表面的ZnSe颗粒越密集,纳米棒的核壳结构越明显,制备的ZnO/ZnSe样品在金卤素灯照射下降解氮氧化物的速率与降解效果也越明显。但考虑到制备过程的便捷、环保等因素,保温温度70℃为制备具有核壳结构的ZnO/ZnSe纳米光催化材料的最佳温度条件。     

纳米TiO2微球的制备及其光催化性能研究

以四氯化钛为钛源,采用无模板溶剂热法合成了纳米TiO_2微球,采用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、紫外-可见分光光度计(UV-Vis)、N_2吸附-脱附等分析方法对样品进行表征,考察水热反应时间对纳米TiO_2微球的形成及光催化降解气相苯的影响。结果表明:纳米TiO_2微球是由锐钛矿相纳米颗粒自组装形成的分级微/纳结构,光吸收出现"蓝移",比表面积高达239.2m~2/g;纳米TiO_2微球的结构参数对其最终的光催化性能影响较大,在水热温度180℃、水热反应时间24h条件下制备的纳米微球表现出最高的光催化活性,其矿化率高于商用P25TiO_2近2倍;纳米TiO_2微球优异的光催化性能得益于其优良的结晶度、相对大的比表面积和丰富的介孔结构。     

改性蛭石负载Fe、N共掺杂TiO_2光催化剂的制备及可见光降解苯酚研究

以改性蛭石为载体,采用水热反应-热处理方法合成了负载型Fe、N共掺杂二氧化钛(TiO_2)纳米光催化材料。利用XRD、UV-Vis DRS、BET和EPR对其结构进行表征。以苯酚溶液为目标降解物,研究所制备样品在可见光下(≥400nm)的光催化活性。结果表明,改性蛭石载体有利于锐钛矿相和大比表面积TiO_2纳米晶的形成;Fe3+和N原子的掺杂及相应产生的氧空位使TiO_2带隙变窄,将光响应范围拓展到了可见光区,同时有利于光生电子-空穴的分离;在可见光照射下,对苯酚具有良好的光催化降解去除效果。     

金红石二氧化钛纳米片的性质及其光催化活性

采用溶胶-凝胶、质子交换和层状剥离的方法, 制备出金红石TiO₂纳米片。利用X射线电子衍射谱(XRD)、透射电子显微镜(TEM)、紫外-可见吸收光谱(UV-Vis)、X光电子能谱(XPS)的价带谱和荧光光谱(PL)等对样品进行了表征, 研究了光生载流子的转移过程。结果证明: 金红石TiO₂纳米片具有较大的比表面积(185.7 m²/g), 厚度约5 nm, 与金红石TiO₂样品相比, 金红石TiO₂纳米片的禁带宽度增加, 氧化还原能力增强; 此外, 纳米片结构能够促使光生载流子快速转移到纳米片的表面并产生有效分离, 阻止了光生电子和空穴的复合, 提高了光催化反应中光生载流子的利用率。金红石纳米片的这些特性导致其具有较高的光催化活性, 紫外光催化降解对氯苯酚的实验表明: 金红石TiO₂纳米片的光催化活性高于金红石TiO₂和锐钛矿TiO₂样品。     

介孔氧化硅/氧化铈核壳双相复合颗粒的制备及其光催化降解活性

将CeO2纳米粒子负载在介孔氧化硅(W-mSiO2)支撑体上,制备了核壳结构的W-mSiO2/CeO2双相光催化复合颗粒.用X射线衍射、扫描电镜、透射电镜、氮气吸脱附、STEM-EDX mapping、Raman光谱、荧光光谱、紫外-可见漫反射光谱等手段分析样品的结构和性质,考察了复合光催化材料对亚甲基蓝(MB)的光催...     

Hydrothermal fabrication of rutile TiO2 submicrospheres on wood surface: An efficient method to prepare UV-protective wood

In this work, wood materials with UV-resistant ability were successfully fabricated by depositing submicrometer-sized rutile TiO₂ spheres on wood surface using a facile and one-pot hydrothermal method. The prepared samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and attenuated total reflectance-Fourier transformation infrared (ATR-FTIR) techniques. ATR-FTIR spectra demonstrated that chemical bonds were formed at the interfaces between rutile TiO₂ and wood owing to the presence of hydroxyl groups. Accelerated aging was used to measure the UV resistance of the original wood (OW), anatase TiO₂/wood (ATW) and rutile TiO₂/wood (RTW). Comparison with OW and ATW samples, RTW exhibited more UV-resistant ability due to high UV light absorption capability, superior light scattering property and high recombination of the photogenerated electron and hole of the submicrometer-sized rutile TiO₂ spheres on the wood surface.     

Preparation and visible-light photocatalytic activity of In2S3/TiO2 composite

A novel In₂S₃/TiO₂ composite with visible-light photocatalytic activity was prepared by a chemical precipitation method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope and UV–vis diffuse reflectance spectroscopy. Under both UV- and visible-light irradiation, the In₂S₃/TiO₂ composite shows good photocatalytic activity to degrade methyl orange, ascribed to the absorption of visible light by In₂S₃ sensitizer and enhanced separation of photoinduced electron–hole pairs in the composite semiconductors.     

Preparation and photocatalytic activity of WO3/TiO2 nanocomposite particles

A novel photocatalyst WO₃/TiO₂ nanocomposite was prepared through a hydrothermal method by using cetyltrimethylammonium bromide (CTAB) as surfactant. The obtained WO₃/TiO₂ was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and diffused reflectance spectroscopy (DRS). Photocatalytic experiments indicate that the nanocomposites show much higher photoactivity than that of pure TiO₂ in the photodegradation reaction of Rhodamine B (RhB). The increased photoactivity of WO₃/TO₂ may be attributed to the improvement of the light absorption properties and the slow down of the recombination between the photoexcited electrons and holes during the photoreaction.     

Visible light photoelectrocatalysis with salicylic acid-modified TiO2 nanotube array electrode for p-nitrophenol degradation

This research focused on immersion method synthesis of visible light active salicylic acid (SA)-modified TiO₂ nanotube array electrode and its photoelectrocatalytic (PEC) activity. The SA-modified TiO₂ nanotube array electrode was synthesized by immersing in SA solution with an anodized TiO₂ nanotube array electrode. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), UV–vis diffuse reflectance spectrum (DRS), and Surface photovoltage (SPV) were used to characterize this electrode. It was found that SA-modified TiO₂ nanotube array electrode absorbed well into visible region and exhibited enhanced visible light PEC activity on the degradation of p-nitrophenol (PNP). The degradation efficiencies increased from 63 to 100% under UV light, and 79–100% under visible light (λ > 400 nm), compared with TiO₂ nanotube array electrode. The enhanced PEC activity of SA-modified TiO₂ nanotube array electrode was attributed to the amount of surface hydroxyl groups introduced by SA-modification and the extension of absorption wavelength range.     

Alternative approaches to fabrication of gold-modified TiO2 nanotubes

Three approaches, impregnation–reduction, deposition and direct assembly, are used to fabricate gold-modified TiO₂ nanotubes. Prepared materials are characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV–visible absorption spectroscopy and BET, etc. The gold-modified TiO₂ nanotubes prepared via various procedures exhibit distinct difference in structure. By impregnation–reduction approach, gold-modified TiO₂ nanotubes with large gold particles are fabricated. The gold particles are either deposited on or encapsulated in TiO₂ nanotubes. However, by using gold hydrophilic colloidal dispersion as gold precursor, gold particles in the modified TiO₂ nanotubes are very small. Gold particles only adhere to the outer surface of TiO₂ nanotubes after deposition process, whereas adhere to not only the outer but also the inner walls of TiO₂ nanotubes after direct assembly process. A possible mechanism is proposed to illustrate the formation of gold-modified nanotubes that are prepared by direct assembly process.     

Mesoporous Au/TiO2 composites preparation,characterization, and photocatalytic properties

In this work, mesoporous Au/TiO₂ composites have been synthesized and tested on photodegradation of methylene blue dye solution. Mesoporous TiO₂ prepared at 450 °C using triblock polymer F127 as structure-directing agent was applied as substrate, while various HAuCl₄ concentrations were used for Au loading through deposition-precipitation method using urea as precipitator and hydrogen reducing process. The influences of Au loading on the microstructures of mesoporous TiO₂ including degree of dispersion, particle size, surface area, light absorption, and band gap were studied with transmission electron microscopy (TEM), X-ray diffraction (XRD), diffuse reflection infrared Fourier transformed spectroscopy (DRIFT), N₂ adsorption–desorption isotherm analysis (BET), and UV–Vis diffuse reflectance spectra. With Au loading, the size of TiO₂ nanoparticles in Au/TiO₂ composites is similar as that of TiO₂ substrate. However, the degree of dispersion was greatly improved. Furthermore, an obvious surface plasmon resonance centered at 570 nm was found in UV–Vis diffuse reflectance spectra for Au/TiO₂ composites. Au loading also induced an obvious red shift of light absorption from UV region to visible region and strengthened both UV and visible light absorption in contrast to substrate. Photodegradation results verified that photocatalytic activity of mesoporous TiO₂ was improved by Au loading. 0.25%Au/TiO₂ composite showed the highest activity, which may be ascribed to its high surface hydroxyl content and the formed Schottky junction after Au loading. These results suggested that noble metal modification is a promising way to synthesize photocatalysts with both high activity and visible light sensitivity.     

Preparation of nitrogen co-doped SiO2/TiO2 thin films on ceramic with enhanced photocatalytic activity under visible-light irradiation

In this study, we have successfully deposited N-doped SiO₂/TiO₂ thin films on ceramic tile substrates by sol–gel method for auto cleaning purpose. After dip coating and annealing process the film was transparent, smooth and had a strong adhesion on the ceramic tile surface. The synthesised catalysts were then characterised by using several analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscope (AFM) and UV-vis absorption spectroscopy (UV-vis). The analytical results revealed that the optical response of the synthesised N-doped SiO₂/TiO₂ thin films was shifted from the ultraviolet to the visible light region. The nitrogen substituted some of the lattice oxygen atoms. The surface area of co-doped catalyst increased, and its photocatalytic efficiency was enhanced. The photocatalytic tests indicated that nitrogen co-doped SiO₂/TiO₂ thin films demonstrated higher than of the SiO₂/TiO₂ activity in decolouring of methylene blue under visible light. The enhanced photocatalytic activity was attributed to an increasing of the surface area and a forming of more hydroxyl groups in the doped catalyst.     

One-pot low-temperature synthesis of BiOX/TiO2 hierarchical composites of adsorption coupled with photocatalysis for quick degradation of colored and colorless organic pollutants

BiOX/TiO₂ (X = Cl, Br, and I) hierarchical composites with superior photoelectrochemical performances were successfully synthesized by one-pot low-temperature solvothermal process without any structure-directing agents. The dual functions of adsorption coupled with photocatalysis based on BiOX/TiO₂ were fully exhibited in terms of the quick degradation of colored and colorless organic pollutants (OPs). The as-prepared composites were characterized by field-emitting scanning electron microscope (FESEM), X-ray power diffraction (XRD) analysis, transmission electron microscope (TEM), N₂ adsorption/desorption, UV–vis diffuse reflectance spectra (DRS), photoluminescence spectra (PL), photocurrent measurements (PC), and electrochemical impedance spectroscopy (EIS), respectively. As-prepared BiOX/TiO₂ composites exhibited outstanding photoelectrochemical activities. Especially, the considerably enhanced adsorption and photocatalytic efficiencies were observed in the optimized BiOCl/TiO₂ composites compared to their counterparts. The improvement of adsorption and photocatalytic performances should be ascribed to the presence of columbite TiO₂-II in anatase, which would not only improve the ability of absorbing visible light and the charge separation efficiency, but also to effectively tailor the particle size, surface area and the exposed active facet of composites.     

Preparation N-F-codoped TiO2 nanorod array by liquid phase deposition as visible light photocatalyst

An efficient method for the preparation of N-F-codoped visible light active TiO₂ nanorod arrays is reported. In the process, simultaneous nitrogen and fluorine doped TiO₂ nanorod arrays on the glass substrates were achieved by liquid phase deposition method using ZnO nanorod arrays as templates with different calcination temperature. The as-prepared samples were characterized by Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectra measurements. It was found that calcination temperature is an important factor influencing the microstructure and the amount of N and F in TiO₂ nanorod arrays samples. The visible light photocatalytic properties were investigated using methylene blue (MB) dye as a model system. The results showed that N-F-codoped TiO₂ nanorod arrays sample calcined at 450 °C demonstrated the best visible light activity in all samples, much higher than that of TiO₂ nanoparticles and P25 particles films.     

Effect of micro-characterization on thrombus formation ability of TiO2 film

The thrombus formation ability of a biomedical microcoil for hemangioma treatment is one of the basic requirements in clinical intervention application. Surface modification of a biomedical microcoil can improve its thrombus formation ability. In this work, TiO₂ films were deposited using the unbalanced magnetron sputtering method. The structures, components and micro-morphologies of the films were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and scanning electron microscope (SEM). The thrombus formation ability of the films was studied by in vitro platelet adhesion test. The results indicated that a certain characteristic TiO₂ film has the ability to increase thrombus formation. Furthermore, the biological behavior of cultured human umbilical vein endothelial cells (HUVECs) onto different films was investigated by an in vitro HUVECs cultured experiment. The results showed that endothelial cells on certain TiO₂ film surfaces have good adherence, growth and proliferation. Additionally, the relationship between the micro-characterization and biological properties of TiO₂ films is discussed.