离子掺杂对纳米TiO2薄膜光催化性能的影响

采用溶胶凝胶法制备含有不同掺杂离子的TiO2溶胶和纳米粉,采用浸渍提拉法将溶胶涂敷在自制的多孔陶瓷膜件上,考察其对蚁酸溶液(1%)的光降解作用。研究结果表明,在适宜掺杂浓度(1?3 ,0.5%La3 (摩尔浓度))下,Fe3 /La3 -TiO2膜的光催化性能最好。采用X射线衍射仪分析、原子力电子显微镜和吸收光谱仪等研究单独掺杂Fe3 、La3 和复合掺杂Fe3 /La3 离子的作用及膜的性能,从而确定出提高TiO2光催化活性的最佳掺杂工艺。     

掺铁纳米TiO_2溶胶改性竹炭研究

采用溶胶-凝胶法常温制备掺铁纳米TiO2溶胶,分析掺铁纳米TiO2溶胶的光催化特性,并采用该溶胶对竹炭进行复合改性,阐明掺铁溶胶改性对竹炭的光催化特性及结构特征的影响机制。结果表明:掺铁纳米TiO2溶胶平均粒度在20nm,为锐钛矿晶型,具有优越的紫外光催化性能及可见光响应能力;掺铁溶胶改性竹炭后,TiO2颗粒主要富集在竹炭表面,赋予竹炭光催化性能,为竹炭长效去除污染、净化空气等功能的开发奠定基础。     

Sol-Gel法制备纳米Fe-TiO_2光催化剂及其光催化性能

以钛酸四正丁酯和无水乙醇为主要原料,掺杂一定比例的Fe3+,采用溶胶-凝胶法(Sol-Gel)制备TiO2-Fe2O3复合催化剂,并用XRD和SEM等手段进行表征。以4-(2-吡啶偶氮)间苯二酚(PAR)光催化降解为模型反应,在可见光条件下对所制备的催化剂催化性能进行表征和评价。结果表明:掺铁TiO2比不掺杂TiO2有更高的催化活性,同时也验证掺铁量在0.5%时,光催化活性最高。焙烧温度在400℃时,催化活性大。     

纳米Fe3+-TiO2涂膜对多孔陶瓷性能的影响

采用溶胶-凝胶法制备了掺杂Fe3 离子的TiO2溶胶,并采用浸渍提拉法在多孔陶瓷上涂敷了该Fe3 -TiO2膜,研究了工艺条件对多孔陶瓷性能的影响.研究结果表明:溶胶的pH值及粘度、掺杂Fe3 离子的量和涂层次数等对多孔陶瓷的性能参数及光催化氧化性能有很大影响;当溶胶的pH值为3～4、溶胶粘度约6 mPa·s、掺杂Fe3 离子量为2.0 g/L左右、涂层次数为2～3次时,制备的多孔陶瓷具有良好的过滤性能和光催化氧化性能.     

溶胶-凝胶法制备TiO2纳米颗粒及其光催化性能

考察了通过溶胶-凝胶法进行过渡金属(Fe3 、Zn2 、Co2 、Ni2 、Cr3 和Sn4 )和稀土元素(La3 、Pr3 、Nd3 、Ce4 、Sm3 、Tb3 、Eu.3 、Gd3 、Y3 和Dy3 )掺杂的TiO2纳米颗粒的光催化活性,以及通过超声波处理反应过程中的溶胶所制备得到的TiO2纳米颗粒的光催化活性.结果表明:0.5%Sn4 、0.5%La3 、0.5%Y3 和0.5%Eu3 (质量分数)掺杂的TiO2纳米颗粒在降解甲基橙溶液的反应中,其光催化活性提高2%～7%;其它的掺杂则使TiO2纳米颗粒的光催化活性降低0.5%～25%;在TiO2纳米颗粒的制备过程中,对溶胶进行超声辐照可使其光催化活性提高15%以上,这是提高TiO2纳米颗粒光催化活性的一条新途径.     

不同掺铁方式对TiO2薄膜光催化活性的影响

采用溶胶凝胶工艺在普通玻璃表面制备出表面掺铁与体相掺铁的TiO2 薄膜。运用SEM ,XRD和AES等技术研究了复合薄膜的表面特征。以光催化降解甲基橙溶液为模型反应 ,表征薄膜的光催化活性。结果表明 :体相掺铁时 ,薄膜的最佳n(Fe) /n(Ti)为 0 .12 %;表面掺铁时 ,薄膜的最佳n(Fe) /n(Ti)为 1.5 %。表面掺铁薄膜的最佳光催化表观速率常数比体相掺铁的最佳值要高 1.5倍。并从载流子分离效率等方面进行了机理探讨。     

Fe3+掺杂TiO2薄膜的制备与表征

利用射频磁控溅射技术在载玻片衬底上沉积了TiO2及Fe3+掺杂的TiO2薄膜,并利用X射线衍射、拉曼光谱和紫外-分光光度计对所制备的薄膜进行了结构与性能表征。结果表明,所制备的TiO2薄膜为锐钛矿相结构,Fe3+掺杂后TiO2薄膜的晶化程度降低,光催化活性减弱。     

B/Fe2O3共掺杂纳米TiO2可见光下的催化性能

采用溶胶凝胶法制备B/Fe2O3共掺杂TiO2复合光催化材料,并用X射线衍射仪(XRD)、扫描电镜(TEM)和紫外可见漫反射光谱(DRS)对粉体进行表征。结果表明:催化剂以锐钛矿存在的纳米颗粒,直观地显示了物质的形貌,掺杂B能极大提高催化剂的可见光响应。以二氯苯酚(DCP)为降解物质,在紫外和可见光下分别研究了复合催化剂的光催化活性。掺杂B能使吸收光谱红移至可见光区,而进一步掺杂Fe2O3大大提高了催化剂的活性。     

溶胶-凝胶法制备前驱物对TiO2/活性炭活性的影响

以无水乙醇为溶剂,二次蒸馏水、浓盐酸及钛酸丁酯的用量为实验参数,考察他们对TiO2溶胶粘度的影响,利用溶胶凝胶法分别制备4种不同的TiO2溶胶,浸涂在活性炭上,形成纳米TiO2/活性炭(TiO2/AC)复合体,通过使用TG-DTA,QELS,SEM,XRD及BET方法考察制备的前驱物对TiO2/AC光催化活性的影响及TiO2凝胶/AC在热处理过程中的物理化学变化.结果表明TiO2溶胶粒度小TiO2纳米颗粒在活性炭上分布均匀;不发生团聚所得的TiO2/AC复合体光催化活性强.     

碳纤维负载Pd-TiO2光催化材料的制备及表征

以PAN基碳纤维为载体,采用溶胶-凝胶法制备碳纤维负载TiO2的光催化材料(TiO2/CF),用常温氧化-还原法在其表面沉积贵金属Pd粒子对其改性,制备碳纤维负载Pd-TiO2的光催化材料(Pd-TiO2/CF).XRD分析表明:采用溶胶-凝胶法在碳纤维表面形成了锐钛矿型TiO2.选择偶氮类染料酸性橙Ⅱ作为光催化降解目标物,用紫外吸收光谱分析等TiO2负载量的TiO2/CF,Pd-TiO2/CF和粉末型TiO2的光催化活性.结果表明:TiO2在负载条件下光催化活性有所下降;Pd粒子沉积可有效提高光催化活性;对于酸性橙Ⅱ溶液,Pd-TiO2/CF光催化活性较TiO2/CF、粉末型TiO2均有显著提高.     

Modification of TiO2 nanorods by Bi2MoO6 nanoparticles for high performance visible-light photocatalysis

In this work, TiO₂ nanorods were prepared by a hydrothermal process and then Bi₂MoO₆ nanoparticles were deposited onto the TiO₂ nanorods by a solvothermal process. The nanostructured Bi₂MoO₆/TiO₂ composites were extensively characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the Bi₂MoO₆/TiO₂ composites was evaluated by degradation of methylene blue. The Bi₂MoO₆/TiO₂ composites exhibit higher catalytic activity than pure Bi₂MoO₆ and TiO₂ for degradation of methylene blue under visible light irradiation (λ > 420 nm). Further investigation revealed that the ratio of Bi₂MoO₆ to TiO₂ in the composites greatly influenced their photocatalytic activity. The experimental results indicated that the composite with Bi₂MoO₆:TiO₂ = 1:3 exhibited the highest photocatalytic activity. The enhancement mechanism of the composite catalysts was also discussed.     

Photocatalytic performance of nano-photocatalyst from TiO2 and Fe2O3 by mechanochemical synthesis

Nano-particles of homogeneous solid solution between TiO₂ and Fe₂O₃ (up to 10 mol%) have been prepared by mechanochemical milling of TiO₂ and yellow Fe₂O₃/red Fe₂O₃/precipitated Fe (OH)₃ using a planetary ball mill. Such novel solid solution cannot be prepared by conventional co-precipitation technique. A preliminary investigation of photocatalytic activity of mixed oxide (TiO₂/Fe₂O₃) on photo-oxidation of different organic dyes like Rhodamine B (RB), Methyl orange (MO), Thymol blue (TB) and Bromocresol green (BG) under visible light (300-W Xe lamp; λ > 420 nm) showed that TiO₂ having 5 mol% of Fe₂O₃ (YFT1) is 3-5 times higher photoactive than that of P25 TiO₂. The XRD result did not show the peaks assigned to the Fe components (for example Fe₂O₃, Fe₃O₄, FeO₃, and Fe metal) on the external surface of the anatase structure in the Fe₂O₃/TiO₂ attained through mechanochemical treatment. This meant that Fe components were well incorporated into the TiO₂ anatase structure. The average crystallite size and particle size of YFT1 were found to be 12 nm and 30 ± 5 nm respectively measured from XRD and TEM conforming to nanodimensions. Together with the Fe component, they absorbed wavelength of above 387 nm. The band slightly shifted to the right without tail broadness, which was the UV absorption of Fe oxide in the Fe₂O₃/TiO₂ particle attained through mechanochemical method. This meant that Fe components were well inserted into the framework of the TiO₂ anatase structure. EPR and magnetic susceptibility show that Fe³⁺ is in low spin state corresponding to μ_B = 1.8 BM. The temperature variation of μ_B shows that Fe³⁺ is well separated from each other and does not have any antiferromagnetic or ferromagnetic interaction. The evidence of Fe³⁺ in TiO₂/Fe₂O₃ alloy is also proved by a new method that is redox titration which is again support by the XPS spectrum.     

Microstructure characterization and photocatalytic activity of mesoporous TiO2 films with ultrafine anatase nanocrystallites

A series of mesoporous TiO₂ films on borosilicate glass with ultrafine anatase nanocrystallites were successfully synthesized using a non-acidic sol gel preparation route, which involves the use of nonionic surfactant Tween 20 as template through a self assembly pathway. The microstructure of these TiO₂ films was characterized by XRD, SEM, HR-TEM, UV-Vis spectroscopy, and N₂ adsorption-desorption isotherm analysis. Their photocatalytic activities were investigated by using creatinine as a model organic contaminate in water. It was found that all mesoporous TiO₂ films prepared with Tween 20 exhibited a partially ordered mesoporous structure. The photocatalytic activity of the TiO₂ films could be remarkably improved by increasing Tween 20 loading in the sol at the range of 50% (v/v), which yielded large amount of catalyst (anatase) on the glass support and enhanced specific surface area. The optimum Tween 20 loading was 50% (v/v) in the sol, above which good adhesion between TiO₂ films and borosilicate glass could not be maintained. The final TiO₂ film (Tween 20: final sol = 50%,v/v) exhibits high BET surface area (∼ 120 m²/g) and pore volume (0.1554 cm³/g), ultrafine anatase nanocrystallinity (7 nm), uniform and crack free surface morphology, and improved photocatalytic activity.     

SnO2@TiO2核-壳纳米线的制备及其光催化性能研究

本文通过固-液-气(VLS)生长机制,利用化学气相沉积法(CVD)制备SnO₂纳米线。利用原子层沉积(ALD)以钛酸四异丙酯为前驱体在SnO₂纳米线表面沉积不同厚度的TiO₂壳层,形成SnO₂@TiO₂核-壳纳米线结构。通过中间Al₂O₃插层,分别制备出金红石和锐钛矿两种不同晶型的TiO₂,从而制备出两种不同复合结构的SnO₂@TiO₂核-壳纳米线。实验研究该复合结构中TiO₂的厚度与晶型对紫外光下光催化降解甲基橙溶液活性的影响。     

TiO2/膨润土复合光催化材料的常温制备及性能研究

采用改进的溶胶-凝胶法,在以水为主要溶剂的反应体系中,控制钛酸四丁酯充分水解、缓慢聚合,在 常压、低温(70℃)的温和条件下制备出稳定的TiO₂纳米晶溶胶,并利用TiO₂纳米晶溶胶在膨润土表面负载,获得TiO₂/膨润土复合光催化材料。采用 X 射线衍射、扫描电镜、比表面积测定等研究手段对样品的结构形貌进行了表征,并考察了其光催化活性。结果表明：较高的水用量有利于TiO₂晶体形成,当去离子水:钛酸四丁酯摩尔比大于167:1时,在溶胶体系中出现了锐钛矿型TiO₂纳米晶体;TiO₂纳米晶主要负载于膨润土表面,并未嵌入到膨润土层间结构,但相对于单一膨润土,TiO₂负载显著提高了材料比表面积;当去离子水:钛酸四丁酯摩尔比=192:1时,在紫外光照射下,复合光催化材料表现出最高的光催化活性,对亚甲基蓝的降解率达到93.8%。     

CC/PANI/TiO2复合材料的制备及其光催化性能研究

先采用原位聚合的方法在碳布上负载聚苯胺,然后利用溶剂热法在制备的碳布/聚苯胺(CC/PANI)复合材料上生长二氧化钛纳米片,得到了可便捷分离的CC/PANI/TiO₂复合光催化材料。通过SEM、XRD、UV、FTIR、XPS等手段对所制备的样品进行了形貌和结构表征,并比较了CC/PANI/TiO₂复合材料和纯TiO₂紫外-可见光条件下催化降解RhB的活性差异,结果表明CC/PANI/TiO₂复合材料具有比TiO₂更优异的光催化活性。光致发光光谱说明CC/PANI/TiO₂复合材料的发光强度比纯TiO₂的弱,有效抑制了光生载流子的复合;瞬态光电流响应和电化学阻抗谱(EIS)证明CC/PANI/TiO₂纳米复合材料更有效促进电子-空穴对分离和提高转移效率;活性物质捕捉实验证实?OH和?O_2^-是复合材料光催化降解RhB过程中的主要活性物质。CC/PANI/TiO₂复合材料循环利用6次后,仍然具有较高的催化活性,显示了其在污水处理领域中的良好应用前景。     

Theoretical study on the electronic and optical properties of (N, Fe)-codoped anatase TiO2 photocatalyst

Electronic and optical properties of pure, N-doped, Fe-doped and (N, Fe)-codoped anatase TiO₂ were evaluated, respectively, by using the density functional theory. The results indicate that the elemental doping narrows the band gap of TiO₂ and realize its visible-light response activity; and incorporation of Fe into N-doped TiO₂ further increases the photocatalytic activity under visible-light irradiation compared with that of the N-doped TiO₂.     

ZnO and TiO2 1D nanostructures for photocatalytic applications

ZnO and TiO₂ 1D nanostructures (nanorods and nanotubes) were prepared by low-cost, low-temperature, solution-based methods and their properties and photocatalytic performance were studied. ZnO nanorod samples with titania and alumina shells were also prepared by solution-based methods, and their properties and photocatalytic performance were compared to that of bare ZnO nanorods. We found that ZnO and TiO₂ exhibited comparable photocatalytic performance. Faster dye degradation under simulated solar illumination was observed for ZnO, while under UV illumination faster degradation was observed for TiO₂. ZnO nanorods with titania shells exhibited inferior photocatalytic performance, while for alumina shells the performance was similar to bare ZnO. Reasons for observed differences are discussed, and the effect of the shell on photocatalytic activity is attributed to the changes in native defects at the ZnO surface/shell interface.     

Characteristics of N-doped TiO2 nanotube arrays by N2-plasma for visible light-driven photocatalysis

N-doped TiO₂ nanotube arrays were prepared by electrochemical anode oxidation of Ti foil followed by treatment with N₂-plasma and subsequent annealed under Ar atmosphere. The morphologies, composition and optical properties of N-doped TiO₂ nanotube arrays were characterized using field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectrometer (XRD), Photoluminescence (PL) and UV-vis diffusion reflection spectroscopy (UV-vis DRS). Methylene blue (MB) solution was utilized as the degradation model to evaluate the photocatalytic activity of the samples under visible light irradiation. The results suggested N₂-plasma treatment created doping of nitrogen onto the surface of photoelectrodes successfully and the N-doped TiO₂ nanotube arrays display a significantly enhancement of the photocatalytic activity comparing with the pure TiO₂ nanotube arrays under the visible light irradiation.     

Effect of Nd2O3 addition on the surface phase of TiO2 and photocatalytic activity studied by UV Raman spectroscopy

TiO₂ modified with Nd₂O₃ (Nd-TiO₂) nanoparticles were prepared by a co-precipitation method and utilized as the photocatalysts for the degradation of Rhodamine B (RhB). The influence of Nd₂O₃ on the bulk and surface phase, surface area, particle size, and optical response of TiO₂ was investigated by X-ray diffraction (XRD), UV Raman spectroscopy, transmission electron microscopy (TEM), BET, and UV-visible diffuse reflectance spectra. It is found that the crystalline phase and phase composition in the bulk and surface region of Nd-TiO₂ calcined at high temperatures can be tuned by changing the amount of Nd₂O₃. Based on the results from XPS, EDX, XRD, and UV Raman spectra, it is assumed that Nd³⁺ ions do not enter the TiO₂ lattice, but highly disperse onto the Nd-TiO₂ particle surface in the form of Nd₂O₃ crystallites. These crystallites inhibit the agglomeration, growth in crystal size, and anatase-to-rutile phase transformation of TiO₂. In the photocatalytic degradation of RhB reaction, Nd-TiO₂ nanoparticles with higher surface area and wider optical response are more reactive in case of the same surface anatase phase. When the mixed phases of anatase and rutile exist in the surface region of Nd-TiO₂, the synergetic effect over surface area and optical response is the important parameter which determines optimal photocatalytic activity.