氮掺杂SrTiO3/TiO2纳米棒异质结的制备及光催化活性

通过水热反应和直接浸渍法在FTO导电玻璃上制备得到了高度有序的氮掺杂SrTiO3/TiO2纳米棒异质结阵列(N-STO/TNR),利用扫描电子显微镜(SEM),X射线衍射(XRD)和X射线光电子能谱(XPS)对其表面形貌,晶体结构和元素价态进行了分析。同时,采用荧光光谱(FL)、紫外可见漫反射光谱(UV-DRS),电化学阻抗谱(EIS)和莫特肖特基(MS)对异质结的光电性能进行了测试。最后以甲基橙为模拟污染物,考察了异质结材料在可见光下的光催化活性。结果表明,SrTiO3/TiO2异质结构能有效的分离光生载流子,同时N元素的掺杂将异质结的光谱响应范围扩展到可见光区,得益于半导体复合和能级修饰策略的协同增强效应,N-STO/TNR展现出优异的光电性能,N-STO/TNR的光催化效率是未改性的TNR样品的5.7倍。     

TiO2/CdS同轴异质结的制备及光催化性能研究

本研究采用阳极氧化法在金属钛箔上制备TiO2纳米管阵列,并用直流电沉积在退火后的TiO2纳米管内部填充CdS。用扫描电子显微镜(SEM)及电子能谱(EDS)、X射线衍射(XRD)对TiO2/CdS异质结进行表征,结果显示,TiO2/CdS同轴核壳结构有序规整排列,孔径大小均一,Cd、S两种元素化学配比接近1:1。450℃空气退火后的TiO2是锐钛矿型,沉积的CdS为六方相。对TiO2纳米管和TiO2/CdS异质结分别进行了紫外–可见吸收光谱和紫外光下光催化降解甲基橙染料的性能测试。结果表明,复合后TiO2的吸收边出现了明显的红移;TiO2/CdS催化降解甲基橙的降解率最高达99.4%,与纯TiO2相比TiO2/CdS的光催化活性明显提高。     

TiO2负载ZnO纳米棒的制备及其光催化性能

采用水热法制备ZnO纳米棒,将TiO2溶胶高速旋涂在ZnO纳米棒的表面,得到TiO2/ZnO复合半导体。通过扫描电子显微镜(SEM)、X射线衍射(XRD)及UV-Vis漫反射等研究样品的表面形貌、晶型结构及光学特性。结果表明:375℃高温焙烧后,TiO2生长成颗粒状,均匀负载在ZnO纳米棒的表面,样品对紫外-可见光的吸收增强。以甲基橙溶液为模拟废水在紫外光辐照下的降解率来评价样品的光催化性能,结果显示,两种半导体复合以后,对光的利用率提高,对甲基橙模拟废水的降解率高于单一半导体。     

Ag-Ag2O/TiO2-g-C3N4纳米复合材料的制备及可见光催化性能

近年来,半导体光催化技术作为一项快速发展的新型环保技术,在降解水体中污染物和可再生清洁能源的生产领域有很大的应用前景。本文以所制备出的20 wt%类石墨烯碳氮化合物(g-C₃N₄)/TiO₂为基质,利用水热法中纳米Ag颗粒部分氧化行为成功合成了Ag修饰异质结型Ag-Ag₂O/TiO₂-g-C₃N₄复合材料。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis DRS)、光致荧光光谱(PL)、瞬态光电流响应等分析测试手段对Ag-Ag₂O/TiO₂-g-C₃N₄复合材料的晶体结构、形貌、光学性质等进行表征和分析。以亚甲基蓝溶液为目标降解物,研究了Ag-Ag₂O/TiO₂-g-C₃N₄复合材料的可见光催化性能。结果表明:在纳米Ag颗粒修饰的Ag-Ag₂O/TiO₂-g-C₃N₄复合材料中,Ag部分氧化成Ag₂O;与g-C₃N₄的协同作用使Ag-Ag₂O/TiO₂-g-C₃N₄复合催化剂具有良好的可见光催化活性;可见光照射4 h后,Ag-Ag₂O/TiO₂-g-C₃N₄复合催化剂对亚甲基蓝的降解率接近50%。      

WS2/g-C3N4异质结光催化分解水制氢性能及机制

通过溶剂蒸发和二次高温煅烧石墨相碳化氮(g-C₃N₄)纳米片和WS₂纳米片混合物构建WS₂/g-C₃N₄异质结,该异质结保留g-C₃N₄和WS₂主体结构的同时,在界面处形成化学键,确保该异质结的化学稳定性和热稳定性。光催化分解水制氢实验表明,WS₂纳米片含量为3wt%时光催化制氢速率高达68.62 μmol/h,分别是g-C₃N₄纳米片和WS₂纳米片的2.53倍和15.29倍,表明异质结的构建可大幅提升g-C₃N₄的光催化性能,循环实验表明该异质结在5次循环实验后光催化性能没有明显下降,表明该异质结的稳定性较好。光电性能测试表明异质结的构建不仅提高激发电子的转移效率,同时抑制激发电子空穴的复合率,大幅提升激发电子的利用效率,致使光催化分解水制氢速率较g-C₃N₄纳米片和WS₂纳米片大幅提升。      

改性TiO2在光催化分解水制氢方面的研究进展

TiO₂光催化剂因具有无毒、稳定性高、氧化还原能力强、成本低等优点而备受关注,然而其禁带宽度较宽只能被紫外光激发,以及光生载流子复合严重等局限性,限制了TiO₂光催化剂的应用。近年来,研究者们对上述问题展开了大量研究,以提高其可见光响应,降低载流子复合,进而提高光催化产氢率。本文综述了对TiO₂光催化剂改性及其在光催化产氢方面的研究进展,并对其今后的发展趋势进行了展望。     

TiO2纳米带制备、表征及光催化性能

采用简单的水热反应以及后续的热处理,制备了大量的TiO2纳米带。通过XRD、SEM、TEM以及UV-Vis对产物进行表征和分析,并以甲基橙作为目标降解物,对退火后的产物进行了光催化性能测试。结果表明,所制备的样品在600℃热处理3h后,样品为锐钛矿相与TiO2(B)相的混晶相。退火以后,带的形态保持较好,带宽约60nm。室温下,所制备的混晶TiO2对甲基橙具有良好的紫外光降解能力,60min后降解度达96%。     

CuO/TiO_2异质多孔纳米结构的制备及其光催化性能

以Cu(OH)_2纳米棒阵列为前驱体,钛酸四丁酯为钛源,采用外向包覆合成法,利用Cu(OH)_2自身热分解产生的微量水分子与负载在其表面的钛酸四丁酯缓慢反应,制备了CuO/TiO_2异质多孔纳米结构,并研究了产物对罗丹明B(RhB)的光催化降解性能。结果表明,得到的产物薄膜为直径2~4μm的微孔组成的多孔纳米结构,微孔的孔壁由直径500nm左右的纳米棒组装而成。产物CuO/TiO_2异质多孔纳米结构比纯TiO_2纳米结构对RhB有更好的光催化降解性能,这主要是由两方面的原因引起的:一方面,CuO/TiO_2异质多孔纳米结构具有更好的吸附性能和更大的比表面积;另一方面,产物CuO/TiO_2为异质复合纳米结构,异质结的存在能有效地降低光生电子空穴对的复合,从而提高产物的光催化降解效果。     

TiO2基异质结光催化剂应用于有机污染物降解的研究进展

光催化技术具有绿色、清洁、环境友好等优点,被广泛应用于降解水体中的有机污染物。其中,TiO₂光催化剂由于其独特的优势,被认为是一种十分具有前景的光催化剂。然而,其本身存在着带隙能较宽可见光响应不足与载流子复合几率高等缺点导致光催化活性受限。为解决以上问题,TiO₂与异质结的结合引起了研究者的兴趣。并且采用一定的改性手段制备的非常规TiO₂基异质结,具有很高的光催化降解能力。但这些新型光催化剂在实际应用中仍具有极大的挑战,例如成本较高、稳定性较差以及副产物毒性风险高等等。基于此,对现有TiO₂基异质结的相关研究进行了系统全面的综述,以期为后续研究提供一定的理论支持。     

BiOCl/Bi2O3异质结复合光催化剂的制备和光催化性能研究

以五水硝酸铋、硝酸、氢氧化钠、盐酸为原料,用盐酸浸渍法制备了盐酸与氧化铋物质的量比分别为0.3∶1、0.5∶1、0.7∶1、1∶1的BiOCl/Bi2O3异质结新型复合光催化剂。用X射线衍射(XRD)、热重-差热分析(TG-DSC)和扫描电子显微镜(SEM)等手段对材料进行了表征。250 W高压汞灯照射下,用光催化降解罗丹明B反应来测试催化剂的光催化活性,结果表明BiOCl/Bi2O3复合光催化剂的性能明显优于单体Bi2O3。当盐酸与氧化铋物质的量比为0.7∶1时,BiOCl/Bi2O3催化剂的光催化活性最佳。最后研究了抑制剂对BiOCl/Bi2O3复合光催化剂降解罗丹明B的影响,发现三乙醇胺和碘化钾都有一定的抑制作用。     

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.     

Emission properties of (SrTiO3-TiO2):Pr eutectic with self-organized fractal microstructure

An investigation of spectroscopic properties of (SrTiO₃-TiO₂):Pr³⁺ eutectic and, for comparison, of bulk SrTiO₃:Pr³⁺ and TiO₂:Pr³⁺crystals is presented. Luminescence spectra have been measured under both 450 nm and 350 nm excitation wavelength. For UV excitation they are characterized by a dominant red luminescence corresponding to transition from the ¹D₂ level of Pr³⁺ ions. The mechanism responsible for quenching of blue (from ³P₀ state) and intensification of red luminescence is proposed to be thermally-induced radiationless relaxation involving a low-lying Pr³⁺-Ti⁴⁺ intervalence charge transfer state. Measured decay constants of ¹D₂ excited state of Pr³⁺ are compared with values obtained for other praseodymium doped titanate hosts.     

Structural and morphological properties of Fe2O3/TiO2 nanocrystals in silica matrix

We report on structural, morphological and ordering properties of Fe₂O₃/TiO₂ nanoparticles embedded in SiO₂-based multilayers. We investigated the structure of these systems by X-ray diffraction and grazing incidence small angle X-ray scattering after post-growth annealing. We found that the presence of TiO₂ promotes the growth and crystallization of the nanocrystals of Fe₂O₃. In multilayers containing both Fe₂O₃ and TiO₂, crystalline nanoparticles create partially ordered three-dimensional arrays.     

Preparation and photoelectrochemical performance of TiO2/HS-CH2-COOH/Cu3Se2 composite film

In this paper, the TiO₂/HS-CH₂-COOH/Cu₃Se₂ composite film photoanodes were fabricated on conducting glass plates. Cu₃Se₂ nanoparticles were used as the sensitizer and the bi-functional modifier HS-CH₂-COOH was used at the interface between Cu₃Se₂ and TiO₂ films to improve the properties of the film photoanode. The characterization results show that the sol-gel prepared anatase TiO₂ film has a compact and uniform surface, while the tetragonal Cu₃Se₂ film has a coarse surface which is made up of uniform elongated particles. The photoelectrochemical experimental results indicate that the TiO₂/HS-CH₂-COOH/Cu₃Se₂ composite film photoanodes have a good photovoltaic property.     

一维TiO2纳米材料的制备及其光催化性能研究

采用水热法,通过改变水热温度成功制备出一系列一维TiO₂纳米管、纳米线和纳米带。运用X射线衍射、透射电子显微镜、N₂吸附-脱附和紫外-可见光谱等手段表征了材料的结构和性质,并考察了一维TiO₂样品光催化降解气相苯的活性。结果表明,一维TiO₂纳米材料具有较高的比表面积,光吸收出现明显的“蓝移”,光催化活性较P25有所提高,其中140 ℃水热温度下制备出的TiO₂纳米管的光催化活性最佳,80 min内对气相苯的去除率为77%,终产物CO₂的浓度为625 mg/m³。     

Determination of photo-catalytic activity of un-doped and Mn-doped TiO2 anatase powders on acetaldehyde under UV and visible light

Titanium dioxide (TiO₂) photocatalytic powder materials doped with various levels of manganese (Mn) were synthesized to be used as additives to wall painting in combating indoor and outdoor air pollution. The heterogeneous photocatalytic degradation of gaseous acetaldehyde (CH₃CHO) on Mn-TiO₂ surfaces under ultraviolet and visible (UV/Vis) irradiation was investigated, by employing the Photochemical Static Reactor coupled with Fourier-Transformed Infrared spectroscopy (PSR/FTIR) technique. Experiments were performed by exposing acetaldehyde (~ 400 Pa) and synthetic air mixtures (~ 1.01 × 10⁵ Pa total pressure) on un-doped TiO₂ and doped with various levels of Mn (0.1-33% mole percentage) under UV and visible irradiation at room temperature. Photoactivation was initiated using either UV or visible light sources with known emission spectra. Initially, the photo-activity of CH₃CHO under the above light sources, and the physical adsorption of CH₃CHO on Mn-TiO₂ samples in the absence of light were determined prior to the photocatalytic experiments. The photocatalytic loss of CH₃CHO on un-doped TiO₂ and Mn-TiO₂ samples in the absence and presence of UV or visible irradiation was measured over a long time period (≈ 60 min), to evaluate their relative photocatalytic activity. The gaseous photocatalytic end products were also determined using absorption FTIR spectroscopy. Carbon dioxide (CO₂) was identified as the main photocatalysis product. It was found that 0.1% Mn-TiO₂ samples resulted in the highest photocatalytic loss of CH₃CHO under visible irradiation. This efficiency was drastically diminished at higher levels of Mn doping (1-33%). The CO₂ yields were the highest for 0.1% Mn-TiO₂ samples under UV irradiation, in agreement with the observed highest CH₃CHO decomposition rates. It was demonstrated that low-level (0.1%) doping of TiO₂ with Mn results in a significant increase of their photocatalytic activity in the visible range, compared to un-doped TiO₂. This elevated activity is lost at high doping levels (1-33%). Finally, the photocatalytic degradation mechanism of CH₃CHO on 0.1% Mn-TiO₂ surfaces under visible irradiation leading to low CO₂ yields is different than that under UV irradiation resulting to high CO₂ yields.     

Investigation on solar photocatalytic activity of TiO2 loaded composite: TiO2/Eggshell, TiO2/Clamshell and TiO2/CaCO3

The TiO₂/Eggshell, TiO₂/Clamshell and TiO₂/CaCO₃ loaded composites were prepared by sol-gel method and characterized by XRD and SEM. Their photocatalytic activities were measured through the degradation of Acid Red B under solar light irradiation. The influences of TiO₂ loaded content, heat-treated temperature and time on the photocatalytic activities were reviewed. The effects of irradiation time and dye initial concentration on the photocatalytic degradation were also investigated. The results showed that the photocatalytic activity can be greatly enhanced by appropriate TiO₂ loaded content.     

Thermo-optic properties of TiO2, Ta2O5 and Al2O3 thin films for integrated optics on silicon

The direct measurement of the thermo-optic coefficients of aluminium oxide, tantalum pentoxide and titanium dioxide thin films is presented. Using ellipsometry on monolithically integrated permutations of the layers of silicon, silicon dioxide and the material under test, allows the direct measurement of the overall thermo-optic coefficient accounting for thermally induced changes in the dielectric permittivity and density of the materials as well as the elasto-optic effect due to the non-matching thermal expansion coefficients of the different materials.     

Microstructural study of YBa2Cu3O7/SrTiO3/YBa2Cu3O7 heteroepitaxial trilayer films grown on (100) SrTiO3 substrates

Detailed transmission electron microscopic study has been carried out on heteroepitaxial YBa₂Cu₃O₇/SrTiO₃/YBa₂Cu₃O₇ trilayer thin films grown on (100)SrTiO₃ substrates prepared by DC and RF magnetron sputtering. The microstructural results showed the existence of somea-axis-oriented YBCO grains 20–90 nm wide in thec-axis-oriented YBCO matrix. Some of thea-axis grains in the lower YBCO thin film layer have protruded into the above SrTiO₃ layer, which may cause short circuit between the two YBCO superconducting layers. This is unsuitable for the application of trilayer thin films for microelectronic devices. The defects on the surface of the substrates would also influence the growth quality of the YBCO thin films.     

溶胶-水热法制备纳米SrTiO3及其表面包覆Al2O3的研究

采用溶胶-水热法制备纳米SrTiO粉体,并采用非均匀形核法在纳米SrTiO3粉体颗粒表面包覆一层Al2O3.借助X射线衍射仪(XRD)、激光粒度分析仪(SL)、红外光谱分析仪(FT-IR)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)对样品进行比较分析.结果表明,用溶胶-水热法制得的SrTiO3粉体颗粒具有较小的粒径,但团聚现象比较严重;经过表面包覆Al2O3后的SrTiO3粉体颗粒粒径小,形状规则,呈球状,分散性好,分布均匀,团聚现象得到改善.