Preparation, Characterization and Photocatalytic Activity of Fe, La Co-doped Nanometer Titanium Dioxide Photocatalysts

A series of photocatalysts of un-doped, single-doped and co-doped nanometer titanium diox- ide （TiO2） have been successfully prepared by template method using Fe（NO3）3.9H2O, La（NO3）3.6H2O, and tetrabutyl titanate as precursors and glucan as template. Scanning electron microscopy, X-ray diffraction, and N2 adsorption-desorption measurement were employed to characterize the morphology, crystal structure and surface structure of the samples. The photo-absorbance of the obtained catalysts was measured by UV-Vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange in an aqueous solution. The characterizations indicated that the prepared photocatalysts consisted of anatase phase and possessed high surface area of ca. 163-176 m2/g. It was shown that the Fe and La co-doped nano-TiO2 could be activated by visible light and could thus be used as an effective catalyst in photo-oxidation reactions. The synergistic effect of Fe and La co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of co-doped nano-TiO2 was also confirmed, the photocatalytic activity of codoped nano-TiO2 remained above 89.6% of the fresh sample after being used four times.

Preparation, Characterization and Photocatalytic Activity of Lanthanum Doped Mesoporous Titanium Dioxide

Lanthanum doped mesoporous titanium dioxide photocatalysts with different La content were synthesized by template method using tetrabutyltitanate （Ti（OC4H9）4） as precursor and Pluronic P123 as template. The catalysts were characterized by thermogravimetric dif ferential thermal analysis, N2 adsorption-desorption measurements, X-ray diffraction, and UV-Vis adsorption spectroscopy. The effect of La3＋ doping concentration from 0.1% to 1% on the photocatalytic activity of mesoporous TiO2 was investigated. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of about 10 nm with high surface area of 165 m2/g. X-ray photoelectron spectroscopy measurements in- dicated the presence of C in the doped samples in addition to La. Compared with pure mesoporous TiO2, the La-doped samples extended the photoabsorption edge into the visible light region. The results of phenol photodecomposition showed that La-doped mesoporous TiO2 exhibited higher photocatalytic activities than pure mesoporous TiO2 under UV and visible light irradiation.

Enhanced photocatalytic activity of (La, N) co-doped TiO_2 by TiCl_4 sol-gel autoigniting synthesis

（La, N） co-doped TiO2 photocatalysts were synthesized using TiC14 sol-gel autoignidng synthesis （SAS） starting from a complex compound system of TiCl4-La（NO3）3-citric acid-NH4NO3-NHyH2O, in which the （La, N） co-doped process was accompushed in the formation of TiO2 nanocrystals. The prepared samples were characterized by using X-ray diffraction （XRD）, X-ray photoemission spectroscopy （XPS） and UV-vis diffuse reflectance spectra. The results indicated that nitrogen and lanthanum were incorporated into the lattice and interstices of titania nanocrystals, which resulted in narrowing the band gap and promoting the separation of photoexcited hole-electron pairs, respectively, and showing expected red-shifts and enhanced photocatalytic activity under visible light. The mechanism on nitrogen doping and enhancement in photocatalyfic activity of （La, N） co-doped titania by SAS was discussed in detail.

Synthesis of TiO_2 films on glass slides by the sol-gel method and their photocatalytic activity

Titanium dioxide （TiO2） films with rod-like and sphere-like TiO2 particles were prepared on glass slides employing the sol-gel method. The shape and size of TiO2 particles were controlled using different concentrations of sodium dodecylbenzensulfonate （SDBS）. By increasing the mole ratio of SDBS, the shape of TiO2 particles transformed from rod-like to sphere-like. Also, the size of TiO2 particles became gradually smaller. Then, the size became bigger when an excess amount of SDBS was added. The films were mainly composed of anatase titania and the relative content of anatase increased with the increasing amount of SDBS. The photocatalytic activity of the TiO2 films that were added with SDBS was higher than that without SDBS. When the concentration of SDBS was 8.0 at%, the sample exhibited the best photocatalytic activity.

Preparation of N-Doped TiO_2-Loaded Halloysite Nanotubes and Its Photocatalytic Activity under Solar-Light Irradiation

The N-doped TiO2-loaded halloysite nanotubes(N-Ti O2/HNTs) nanocomposites were prepared by using chemical vapor deposition method which was realized in autoclave. The photocatalytic activity of nanocomposites was evaluated by virtue of the decomposition of formaldehyde gas under solar-light irradiation. The XRD patterns verified that the anatase structured TiO2 was deposited on HNTs. The TEM images showed that the surface of HNTs was covered with nanosized TiO2 with a particle size of ca. 20 nm. The UV-vis spectra indicated that the N-Ti O2/HNTs presented a significant absorption band in the visible region between 400 nm and 600 nm. Under solar-light irradiation, the highest degradation rate of formaldehyde gas attained 90% after 100 min of solar-light irradiation. The combination of the photocatalytic property of TiO2 and the unique structure of halloysite would assert a promising perspective in degradation of organic pollutants.

Preparation of Rectorite-TiO_2 and Its Application in the Solar Photocatalytic Degradation of Dye Wastewater

A photocatalyst consisting of TiO2 powder and rectorite was prepared and activated utilizing solar light and used for degradation of simulated dye wastewater （methyl solution）. The effects of roasting temperature, the way of adding rectorite, and the amount of the rectorite on the photocatalytic activity have been investigated. The results indicated that rectorite-TiO2 photocatalyst prepared with the right proportional amount of rectorite and titanium dioxide, could effectively degrade the methyl orange solution in sunlight. After reacting in sunlight for 8 hours, the methyl orange decolorization reached 96%. The photocatalytic activity of rectorite-TiO2 was much better than that of TiO2 in sunlight.

Preparation of Photocatalytic TiO_2 and TiO_2-SiO_2 Particles and Application to Degradation of Trace Organics in Aqueous Solution

TiO2 and TiO2-SiO2 photocatalysts were prepared by sol-gel and supercritical CO2 fluid drying method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), etc. Their catalytic properties were tested through the photocatalytic degradation of phenol and aniline in wastewater. The results show that the developed fluidized photocatalytic reactor (FPR) and TiO2 catalyst had better performance in degrading pollutants as compared with slurry photocatalytic reactor (SPR) and commercial TiO2 catalyst. The composition and crystal form of TiO2-SiO2 composite oxide had obvious influence on catalytic effect and TiO2-SiO2 photocatalysts showed better catalytic activity and stability.

Preparation and performance of photocatalytic regenerationable activated carbon prepared via sol-gel TiO_2

Preparation of photocatalytic regenerationable activated carbon （AC） is the key step for the practical application of in situ regeneration of exhausted AC. A novel photocatalytic regenerationable AC was prepared by sol-gel TiO2 in this work. The adsorption and regeneration performance of TiO2/AC were evaluated using phenol as model compound. Scanning electron microscope （SEM） and nitrogen （77 K） adsorption isotherm were used to determine the surface area, pore structure and the distribution of TiO2. The results showed that with the increase of TiO2 loading, adsorption capacity of TiO2/AC decreased and the regeneration efficiency increased. The photocatalytic regenerationable AC with suitable TiO2 loading （2 wt%） exhibited suitable adsorption capacity and regeneration efficiency. TiO2 located mainly in the entrance of macro-pore of carbon. The prepared TiO2/AC exhibited similar surface structure and pore structure with material carbon.

Preparation and characterization of (metal, nitrogen)-codoped TiO_2 by TiCl_4 sol-gel auto-igniting synthesis

The nitrogen-doped and （metal, nitrogen）-codoped TiO2 photocatalysts （metal = Ag, Ce, Fe, La） were synthesized by sol-gel auto-igniting synthesis （SAS） with the complex compound sol of TiCl4-NH4NO3-citri acid-metal nitrate- NH3.H20 as a precursor. The products were characterized by means of XRD, XPS, and UV-Vis diffuse reflectance spectra, and their photocatalytic activity was investigated under visible light. It was found that all the synthesized powders showed good absorption for visible light, and that the radius and alterable valence states of doping metallic cations played important roles on their photocatalytic activity. These results were discussed in detail.

TiO_2/ACF复合材料的Sol-Gel法制备及其对苯的去除性能

以钛酸四丁酯为钛源,采用改进溶胶-凝胶法合成TiO2前驱体;采用浸渍-提拉法将TiO2前驱体负载在活性炭纤维(ACF)表面制得TiO2/ACF复合材料.采用X射线衍射(XRD)、扫描电镜(SEM)、低温液氮吸附等对TiO2/ACF复合材料晶相结构、表面结构等进行了表征.在静态自制光催化反应装置中紫外光照射条件下,以高浓度(2926.5mg/m3)气态苯考察TiO2/ACF对气相有机污染物的去除性能,以气相色谱-质谱(GC-MS)检测中间产物种类与分布.结果表明:TiO2于ACF表面形成完整薄层,随负载次数增加,TiO2/ACF比表面积下降;TiO2薄层变厚、开裂,甚至脱落.400℃煅烧时TiO2已完全转变为锐钛矿相,随煅烧温度升高,锐钛矿型TiO2晶粒尺寸变大,至700℃时开始有金红石相生成.负载2次,400℃煅烧TiO2/ACF复合材料TiO2/ACF-400-2表现出最高活性.TiO2/ACF对苯的去除过程中未检测到毒性较大的酚、醌类中间产物.

Photocatalytic Activity of Hierarchical Flower-Like TiO_(2) Superstructures with Dominant {001} Facets

The fabrication of well defined hierarchical structures of anatase TiO_(2) with a high percentage of reactive facets is of great importance and challenging.Hierarchically flower-like TiO_(2) superstructures(HFTS)self-assembled from anatase TiO_(2) nanosheets with exposed{001}facets(up to 87%)were synthesized by a simple alcohothermal strategy in a HF-H_(2)O-C_(2)H_(5)OH mixed solution using titanate nanotubes as precursor.The samples were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and N2 adsorption-desorption isotherms.The photocatalytic activity was evaluated by the photocatalytic oxidation decomposition of acetone in air and methyl orange in aqueous solution under UV illumination.The photocatalytic activity of HFTS was much higher than that of commercial Degussa P25 and tabular-shaped anatase TiO_(2) obtained using pure water as the synthesis medium.The enhancement in photocatalytic activity was related to several factors,including the hierarchically porous structure,exposed{001}facets,and increased light harvesting ability.The HFTS was also of interest for use in solar cells,photocatalytic H_(2) production,optoelectronic devices,sensors,and catalysis.

Influences of additives on phosphoric acid treatment of titanium dioxide as a novel white pigment

Titanium dioxide is a photocatalytically active substance used as a white pigment for cosmetics.In sunlight,titanium dioxide catalyzes decomposition of a certain amount of sebum on the skin by ultraviolet radiation.Herein,a novel white pigment for use in cosmetics was developed from titanium dioxide and phosphoric acid at pH=4 with and without glycerin,sodium lactate,lactic acid,and urea.The chemical composition,powder properties,photocatalytic activity,color phase,and smoothness of the samples were studied.Addition of glycerin led to a decline in the intensity of the X-ray diffraction(XRD)peak of TiO_(2) relative to that of the other samples.The particle size of the materials prepared with and without additives was 0.3μm;however,extensive aggregation was observed in the obtained materials.The photocatalytic activity of TiO_(2) was inhibited by phosphoric acid treatment.The materials prepared with sodium lactate,lactic acid,and glycerin exhibited higher photocatalytic activity than that prepared without additives.The obtained materials showed a high reflectance in the range of visible light,and the L^(*)values in L^(*)a^(*)b^(*) color space were high(where L^(*)defines lightness,a^(*) denotes the red/green value,and b^(*) the yellow/blue value).These results indicate that the samples prepared in this work are suitable for use as white pigments.

Liquid phase heterogeneous photocatalytic ozonation of phenol in liquid-solid fluidized bed:Simplified kinetic modeling

The isotherms of original AC （activated carbon） and photocatalysts （TiO2-AC） calcined at 500 ℃ for phenol were measured. The results showed a reversible adsorption of phenol onto both kinds of particles at 25 ℃, and could be fitted well to the Freundlich adsorption equation for the dilute solution. Five oxidation processes, namely O3, O3 [UV, O3/UV/AC, O2/UV/TiO2 and O3/UV/TiO2, for phenol degradation in fluidized bed were evaluated and compared, and the photocatalytic ozonation was found to give the highest phenol conversion because of the combined actions of homogenous ozonafion in the liquid phase, heterogeneous ozonation on the surface of the catalyst support, i.e. activated carbon, and heterogeneous photocatalytic oxidation on the TiO2 catalyst surface. With the simplified kinetic model, photolytic ozonation was confirmed to predominantly take place on the particle surface in comparison with the heterogeneous and homogeneous photolytic ozonation. Additionally, the heterogeneous photocatalytic oxidation constant was found to be enhanced by 3.73 times in photocatlaytic ozonation process with ozone as the scavenger compared to the photocatalytic oxidation process with oxygen as the scavenger.

Responding Depth of Photocatalytic Activity of TiO_2 Self-assembled Films

The electrostatically self-assembly method is getting strategically important to prepare multilayer thin films. With careful choice of component materials, this method should allow for the preparation of multilayer thin films with a variety of excellent technological properties. Ti02/PSS multilayer thin films with ordered structure were prepared by electrostatic self-assembly method. UV-Vis-NIR spectrophotometer, X-ray photoelectron spectroscopy (XPS), and atom force microscopy (AFM) were used to characterize the structure and performance of the multilayer films. Because electrostatically self-assembly method allows molecular-level control over the film composition and thickness, this paper studied the responding depth of photocatalytic activity of Ti02 self-assembled films in detail.

Photocatalytic Activity of Nanosized TiO_2 Enhanced by co-doping with Fe^(3+) and Nd^(3+) Ions

In this study, nanosized TiO2 co-doped with Fe3+ and Nd3+ ions was synthesized via a sol-gel method. The metallic ion doped TiO2 was thoroughly characterized with XRD and UV-vis, and the photocatalytic activity was evaluated by degrading methylene blue (MB) solution. The results indicated that TiO2 crystalline size was reduced and phase transformation of anatase to rutile was suppressed as the content of doped Nd3+ ion increased in the co-doped TiO2. The UV-vis spectra of co-doped TiO2 seemed to simply overlay two spectra of single metal doped TiO2, and had significantly increased absorbance in the ranges of 400～500 nm, 565～600 nm and 730～765 nm as compared to pure TiO2. The photocatalytic activity of co-doped TiO2 was obviously enhanced, and raised about 30% compared to that of pure TiO2 as doped Nd3+ content was 0.15% and Fe3+ content was 0.05%, respectively. The enhanced catalytic activity was attributed to a synergistic effect of two doped ions, where doped Fe3+ ion inhibited the recombination of photogenerated electron and hole, and Nd3+ ion brought more surface carboxyl to promote the degradation reaction.

具有增强光催化和抗菌活性的TiO_(2)@Ag-GO复合材料

光催化降解环境中的污染物被认为一种理想的清洁方法,其中二氧化钛(TiO_(2))是目前最有前途的光催化材料之一。但由于能带宽、光生电子与空穴快速复合等特点,限制了其利用效率和范围,开发一种高效的TiO_(2)基光催化复合材料具有重要意义。通过简单的溶胶-凝胶法和一步Marangoni法,将TiO_(2)和Ag纳米颗粒(AgNPs)和氧化石墨烯(GO)有效结合,制备出显著增强光催化活性和抗菌能力的复合材料TiO_(2)@Ag-GO。氧化石墨烯(GO)具有多个催化活性中心,可以高效地进行光催化反应降解污染物。同时,还能提高电荷分离程度,抑制光生电子和空穴复合,提高TiO_(2)光催化活性。AgNPs具有存储电子和促进电荷分离的能力,同时释放的Ag+,赋予材料广谱的抗菌性能。光催化试验抑菌试验结果表明,复合材料能高效降解亚甲基蓝染料,2 h降解率达到74.5%,同时对金黄色葡萄球菌和铜绿杆菌有较强的杀灭作用。这种简易制备的高催化和杀菌功能的TiO_(2)基复合材料在光催化清洁领域有很大的应用潜力。

Preparation of nano-TiO_2/diatomite-based porous ceramics and their photocatalytic kinetics for formaldehyde degradation

Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differential thermal analysis, and the phase and microstructure were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicated that the carriers were encapsulated by nano-TiO2 with a thickness of 300-450 nm. The main crystalline phase of TiO2 calcined at 650~C was anatase, and the average grain size was 8.3 nm. The FT-IR absorption bands at 955.38 cm1 suggested that new chemical bonds among Ti, O, and Si had formed in the composites. The photocatalytic （PC） activity of the composites was investigated un- der UV irradiation. Furthermore, the photodegradation kinetics of formaldehyde was investigated using the composites as the cores of an air cleaner. A kinetics study showed that the reaction rate constants of the gas-phase PC reaction of formaldehyde were k = 0.576 mg＇m3·min^-1 and K = 0.048 m3/mg.

Preparation of TiO_2 Thin Film and Its Antibacterial Activity

TiO 2 nanometer thin films with photocatalytic antibacterial activity were prepared by the sol-gel method on fused quartz and soda lime glass precoated with a SiO 2 layer.The thin films were characterized by X-ray photoelectron spectroscopy (XPS),scanning electron microscopy (SEM),and X-ray diffraction (XRD).The results show that sodium and calcium diffusion into nascent TiO 2 film is effectively retarded by the SiO 2 layer precoated on the soda lime glass.The antibacterial activity of the films was determined.The crystalline of TiO 2 nanometer thin film has important effects on the antibacterial activity of the film.

Preparation and photocatalytic properties of Fe-doped TiO_2 nanoparticles

Nanocrystalline Fe-doped TiO2 with size of 6070 nm was prepared by a sol-gel technique, followed by freeze-drying treatment for 2 h. Thermogravimetric and differential thermal analyses, X-ray diffraction, scanning （electron） microscope, laser diffraction particle size analyzer and UV-Vis spectrophotometer technologies were used to characterize the product. The photocatalytic activities of the samples were evaluated by the degradation of wastewater of paper-making. The effects of Fe ion implantation on the photocatalytic activity of TiO2 were also discussed. The results show that the iron content plays an essential role in affecting the photocatalytic activity of the Fe-doped TiO2 and the optimum content of Fe-doped is 0.05% （mass fraction）. The photocatalytic activity of samples with lower content of Fe-doped is higher than that of pure TiO2 in the treatment of paper-making wastewater. The photo-degradation effect of paper-making effluent is the best by means of Fe-doped TiO2 with 0.05% Fe.

Synthesis and photocatalytic properties of lanthanum doped anatase TiO_2 coated Fe_3O_4 composites

A composite photocatalyst （La/TiO2/Fe3O4） with a lanthanum doped TiO2 （La/TiO2） shell and a magnetite core was prepared by coating photoactive La/TiO2 onto a magnetic Fe3O4 core. The morphological, structural, and optical properties of as-prepared samples were charac-terized by transmission electron microscopy （TEM）, X-ray diffraction （XRD） and UV-vis absorption spectroscopy. The effect of lanthanum content on the photocatalytic properties was studied, and the result revealed that 0.15 mol% La/TiO2/Fe3O4 exhibited the highest photoactiv-ity. The photocatalytic properties of the prepared photocatalyst under UV and visible light were investigated in aqueous solution using methyl orange （MO） as a target pollutant. The results showed that the prepared photocatalyst was activated by visible light and used as an ef-fective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, La/TiO2 was tightly bound to Fe3O4 and could be easily recovered from the medium by a simple magnetic process.