N-doped TiO2/ZnO composite powder and its photocatalytic performance for degradation of methyl orange

The N-doped TiO₂/ZnO composite powder with a molar ratio of Ti to Zn of 3/1 was prepared via sol–gel process and then ammonia treated with NH₃ mass fractions of 0%, 7%, and 28% for 24 h at room temperature followed by thermal calcinations in air for 2 h at various temperatures of 500, 600, and 700 °C. The as-prepared composite powder was characterized in detail through thermo-gravimetric analyzer, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The results showed that the phase transformation of anatase to rutile has been successfully retarded via the ammonia treating process, leading to the presence of anatase phase in the composite. The particle crystallization of the composite powder was significantly promoted with the increase of the calcining temperature. The photocatalysis evaluation through MO degradation revealed an enhanced photocatalytic activity for the composite powder that might be related to the good crystallization, the presence of anatase phase, and the particle size reduction of the powder.     

水热制备TiO2纳米管及其光催化性能

本文利用TiO₂粉体在高浓度NaOH溶液中水热反应制备TiO₂纳米管,采用X射线衍射(XRD)、扫描电镜(SEM),透射电镜(TEM),紫外可见分光光度计(UV-Vis)考察了NaOH浓度、水热反应温度、水热反应时间等因素对TiO₂纳米管结构和性能的影响。结果表明：当NaOH浓度为10mol/L,水热反应温度为160℃,水热反应时间20h时,所制备的TiO₂纳米管显示出较高的光催化活性,经紫外光照30min后,对甲基橙(MO)的降解率可达75.48%。     

N-doped TiO2 nanotube arrays: Synthesis by anodic oxidation in an Ionic Liquid ([BMIM]BF4) and Assessment of Photocatalytic Properties

本文简述了以HF水溶液为电解液,离子液体（1-丁基-3-甲基咪唑四氟硼酸盐 [BMIM]BF4）为N源,采用阳极氧化法制备N掺杂TiO2纳米管阵列。通过扫描电子显微镜(SEM)、X射线衍射光谱(XRD)、X射线光电子能谱（XPS）、傅里叶变换红外光谱（FT-IR）和紫外-可见漫反射光谱（DRS）对N掺杂TiO2纳米管阵列的表面形貌、晶型和氮元素的掺杂方式进行分析。以球形氙灯为光源,亚甲基蓝溶液为目标物质测试N掺杂TiO2纳米管阵列的光催化活性。N掺杂TiO2纳米管阵列对亚甲基蓝溶液的降解率明显高于未掺杂的TiO2纳米管阵列。这是因为N掺杂后产生杂质能级使禁带宽度变窄,并且N掺杂进入TiO2晶格中形成O-Ti-N 键和Ti- O-N键,使氧空位数量增加,从而使光催化活性提高。     

Structure differences between TiO2 and phosphorus implanted TiO2 films caused by thermal treatment

The titanium oxide film has been deposited on Si wafers (110) by unbalance reactive magnetron sputtering and modified by phosphorus ion implantation and succeeding vacuum annealing. The structural, states of surface chemistry and surface morphology of the films have been investigated by X-ray diffraction (XRD), X-ray photoelectric spectroscopy (XPS), atomic force microscope (AFM) and Scanning Electron Microscope (SEM), respectively. The results of XRD show rutile structure of as-deposited film, which is not changed by phosphorus implantation and vacuum annealing. However, a slightly shift of the peaks position to higher degree and the half width increases after ion implanted and vacuum annealing represent that the variety of the structure film caused by these treatments. The surface roughness is inclined to increase with the rising of annealing temperature for both undoped and P doped titanium oxide films. The surface chemistry presents significant difference between undoped and phosphorus doped films after a vacuum annealing, it may be attributed to the different evolvement of the surface defects existing in the film, which may be considered as an important influencing factor in the blood compatibility of the titanium oxide film.     

Photocatalytic bactericidal effect of TiO2 thin film on plant pathogens

Many plant pathogens such as Enterobacter spp., Pythium spp., and Fusarium spp. can be transmitted by irrigation water. The conventional bactericidal methods often apply chemical pesticides to the water. However, synthetic pesticides are hazardous to animals and the environment. Photochemical disinfection of plant pathogens with TiO₂ thin film might offer an alternative method to disinfect plant pathogens from water. In this study, photocatalytic inactivation of Enterobacter cloacae SM1 and Erwinia carotovora subsp. carotovora ZL1 was evaluated on glass substrates coated with TiO₂ thin film using the sol-gel process. The bactericidal activity was examined with 2, 3, 5-triphenyl tetrazolium chloride (TTC), an indicator of cell viability. The inhibition rates of TiO₂ thin film against E. cloacae SM1 and E. carotovora subsp. carotovora ZL1 bacteria treated with ultraviolet A (UV-A) light irradiation for 60 min were 99.5% and 99.9%, respectively. The disinfection efficiency with TiO₂ thin film is relatively constant at pH values in the range of 5.8 to 8.0. The results suggested that photocatalytic phytopathogen inactivation with TiO₂ thin film has the potential for use as a new tool for plant protection in recycled water systems.     

Primary investigation of corrosion resistance of Ni-P/TiO2 composite film on sintered NdFeB permanent magnet

In this paper, an electroless nickel plating and sol-gel combined technique used to prepare the Ni-P/TiO₂ composite film on sintered NdFeB permanent magnet is described and the composite film was characterized by X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), and energy dispersive X-ray spectrometer (EDX). The corrosion resistance of Ni-P/TiO₂ film was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The self-corrosion current density (i_corr) of Ni-P/TiO₂ composite film is 2.38μA/cm² in 0.5mol/L H₂SO₄ solution about 33% of that of Ni-P coating and 0.22μA/cm² in 0.5mol/L NaCl solution about 14% of that of Ni-P coating, respectively. In 0.5mol/L H₂SO₄ and 0.5mol/L NaCl solutions, the polarization resistance (Rp) of the composite film is 12.5kΩ cm² and 120kΩ cm², about 1.6 and 2 times that of Ni-P coating, respectively. The results indicate that Ni-P/TiO₂ composite film has a better corrosion resistance than Ni-P coating.     

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 effects of TiO2/Fe thin film irradiated with visible light on cellular surface ultrastructure and genomic DNA of bacteria

TiO₂/Fe thin film is thin film modified by metal (Fe) plasma ion implantation. In our previous work, it has been demonstrated to have antimicrobial activity after being irradiated with visible light. However, the mechanism of its antimicrobial activity has not been well known yet. In this study, the effects of TiO₂/Fe thin film irradiated with visible light on the cellular morphology and DNA of the Erwinia carotovora subsp. carotovora ZL1, an important soft rot bacterium of vegetable and ornamental crops were examined. Scanning electron microscopic studies revealed that abnormal ultrastructures were observed on the surface of E. carotovora subsp. carotovora ZL1 cells treated with TiO₂/Fe thin films irradiated with visible light for 60 min. Based on the gel electrophoresis analysis, the genomic DNA of E. carotovora subsp. carotovora ZL1 cells treated with TiO₂/Fe thin films under visible light irradiation was also affected. The results suggest that TiO₂/Fe thin film irradiated with visible light has the potential to disinfect of plant- or public health-concerned pathogens.     

Deposition of TiO2 thin films on steel using a microwave activated chemical bath

Microwave activated chemical bath deposition (MW-CBD) is a simple and novel technique in which the substrate is heated directly by microwaves and very well adhered layers are obtained. It has not been used previously for TiO₂ deposition on metals. We show that it is possible to coat stainless steel with TiO₂ using MW-CBD. Two different precursor solutions are used for TiO₂ deposition on steel grade 316. TiO₂ thin films on steel substrates were characterized using SEM and Raman spectroscopy. Raman analysis showed that amorphous TiO₂ is obtained using the precursor solution based on TiOSO₄; however, films show anatase crystal structure when using the precursor solution based on (NH₄)₂TiF₆. Thermal treatment of the films improved crystallinity and also allowed iron diffusion from the steel substrate into the film. Crystalline phases that appeared due to heat treatment were identified from Raman spectra. MW-CBD allows simple low temperature coating of a metal substrate with TiO₂ and this should be useful for a number of different applications.     

Photo-catalytic effect enhanced by the chemisorption of phenylethyl-mercaptan-assembled monolayers on Au-clusters/TiO2-anatase thin film

A simple process is employed to increase the efficiency of TiO₂ photo-catalytic activity, for which the recombination probability of electron–hole pairs is relaxed. Au is selectively deposited on a high-transparency TiO₂-anatase thin film on a glass substrate, and then phenylethyl mercaptan (PEM) is chemisorbed onto the selectively covered Au-clusters/TiO₂-anatase thin film. The enhancement of the photo-catalytic activity on the PEM/Au-clusters/TiO₂-anatase thin film is evaluated via the induced degradation of methylene blue. The results demonstrate that the Au coverage ratio on TiO₂-anatase thin film and the photo-catalytic activity of the chemisorbed PEM/Au-clusters/TiO₂-anatase are related. The photo-catalytic contribution of PEM/Au-clusters/TiO₂-anatase differs from that of Au on a TiO₂-anatase thin film. An optimized photo-catalytic system, a composite of PEM/3.8% Au-clusters/TiO₂-anatase thin film, is proposed. The efficiency of the PEM/3.8% Au-clusters/TiO₂-anatase thin film is 52.1% higher than that of the as-deposited TiO₂-anatase thin film.     

Electrodeposition of sol-enhanced nanostructured Ni-TiO2 composite coatings

A novel electroplating method has been developed to produce nanocrystalline metal-matrix nano-structured composite coatings. A small amount of transparent TiO₂ sol was added into the traditional electroplating Ni solution, leading to the formation of nanocrystalline Ni-TiO₂ composite coatings. These coatings have a smooth surface. The Ni nodules changed from traditional pyramid-like shape to spherical shape. The grain size of Ni was also significantly reduced to the level of 50 nm. It was found that the amorphous anatase TiO₂ nano-particles (∼ 10 nm) were highly dispersed in the coating matrix. The microhardness was significantly increased from 320 HV₁₀₀ of the traditional Ni coating to 430 HV₁₀₀ of the novel composite coating with 3.26 wt.% TiO₂. Correspondingly, the wear resistance of the composite coating was improved by ∼ 50%.     

Effect of polyethylene glycol on hydrophilic TiO2 films: Porosity-driven superhydrophilicity

Polyethylene glycol (PEG) 2000 was used as a templating reagent to synthesize porous TiO₂ thin film by sol-gel process. The nanopores resulting from the presence of growing cracks were ultimately formed on the surface when PEG content was higher than the critical value. Surprisingly, stable pore structure disappeared and surface became fluctuating and dehiscent after PEG amount increased to 0.02 M. Besides, two main hypotheses were proposed in order to explain this superhydrophilic behavior, namely the Wenzel and Cassie wetting impregnating models. Furthermore, the transition between these two wetting regimes was investigated and the criteria for the design and construction of Cassie impregnating wetting surface was also discussed. It was found that Cassie state shifting from Wenzel state could be easily achieved with increasing hole depth on TiO₂ surface. The study of transition between Wenzel and Cassie impregnating wetting regimes on porous films provides valuable wetting mechanism of porosity-driven wettability for the design of superhydrophilic surfaces.     

Charge transport and recombination in dye-sensitized solar cells based on hybrid films of TiO2 particles/TiO2 nanotubes

In this paper, anodic TiO₂ nanotubes are blended into the TiO₂ mesoporous films based on P25 nanoparticles to assemble a list of dye-sensitized solar cells (DSSCs) with different nanotube concentrations. The electron properties of transport and recombination in the fabricated DSSCs are studied by using electrochemical impedance spectroscopy and the open-circuit voltage decay technique under AM 1.5 illumination. Results indicate that the electron lifetime increases with increasing the concentration of the anodic TiO₂ nanotubes, the electron transport time at a blending level of 10 wt% TiO₂ nanotubes is short as compared to that at 0 wt%, and above 10 wt%, the electron transport time has a trend of becoming large. Due to the combining effects of the electron transport and recombination, the electron collecting efficiency and the electron diffusion length obtain maxima at a blending level of 10 wt% nanotubes, which results in a highest short circuit current and a maximum energy conversion efficiency at this point in the DSSCs. This study gives a clear explanation for the performance enhancement of TiO₂ particle-based DSSCs at a blending level of 10 wt% anodic TiO₂ nanotubes and for the performance decrease at a blending level over 10 wt% anodic TiO₂ nanotubes from the angle of the electron transport and recombination. This study also supplies a feasible and easy way to improve the performance of particle-based DSSCs by restraining electron recombination and accelerating electron transportation.     

阳极氧化制备工艺对TiO_2纳米管阵列显微形貌的影响

为改善TiO_2纳米管阵列结构有序性和形貌完整性,以NH4F-丙三醇-水溶液为电解液,采用一次阳极氧化法和二次阳极氧化法在Ti片表面制备TiO_2纳米管阵列,借助扫描电子显微镜和原子力显微镜,研究一次阳极氧化电压、二次阳极氧化法制备过程中阳极氧化电压和一次阳极氧化时间以及退火温度对TiO_2纳米管阵列显微形貌的影响。结果表明,采用一次阳极氧化法在5~25 V电压下阳极氧化Ti片120 min后均可制得有序排列的TiO_2纳米管阵列,纳米管外侧面具有"竹节状"结构特征,纳米管平均管径和管间距随氧化电压升高而增大;一次阳极氧化法在20 V/120 min下制得的TiO_2纳米管阵列相对较优,其表面平整度高。在相同氧化电压下采用二次阳极氧化法制备TiO_2纳米管阵列不能有效改善阵列的有序程度和表面平整度。600℃退火会促进TiO_2纳米管层/钛金属界面处的热氧化物层生长。     

In situ template polymerization of aniline on the surface of negatively charged TiO2 nanoparticles

The in situ oxidative template polymerization of aniline was performed successfully on the surface of negatively charged titania (TiO₂) nanoparticles with a mean diameter of 40 nm using ammonium persulfate and a Chem-Solv solution at pH 1 and 25 °C. SEM showed that the resulting polyaniline (PANI)/TiO₂ composites were well dispersed in solution due to the electrostatic repulsion force. Ultraviolet/visible spectroscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, and cyclic voltammetry showed that the optical, thermal, and electrical properties of PANI/TiO₂ composites were quite different from those of pure PANI or TiO₂, which was attributed to the strong interaction between the two components. The conductivity of the PANI/TiO₂ composite was estimated to be 0.91 × 10⁻¹ S/cm at 25 °C in the range of semiconductor.     

纳米颗粒增强TiO_2涂层的制备及其防污性能

为提高二氧化钛涂层的防污性能,采用KH-550硅烷改性锐钛矿型TiO_2颗粒,并充分分散于二氧化钛凝胶涂层中。通过降解亚甲基蓝溶液、细菌贴附试验、藻类贴附试验,分别评价了涂层的光催化性能、抗菌性能及抗藻类附着性能,并利用激光共聚焦显微镜及扫描电子显微镜对藻类在涂层表面的附着情况进行分析。结果表明,添加TiO_2纳米颗粒涂层的防污性能较未添加TiO_2纳米颗粒涂层有较大程度的提高。添加粒径为5~10 nm TiO_2颗粒的二氧化钛涂层对小球藻、三角褐指藻及小新月菱形藻的附着降低率分别达到了92.1%、71.5%和62.1%,相较于纯二氧化钛涂层对3种藻类的附着降低率分别提高了29.7%、68.4%和43.5%。TiO_2颗粒的加入可以有效地提高涂层的光催化性能,光催化使得涂层具有亲水、抗菌及自清洁的性能进而有利于提高涂层的防污性能。     

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.     

TiO2纳米阵列超疏水膜的制备及耐腐蚀性能

采用阳极氧化法在纯钛表面制备TiO2纳米管阵列,使用六甲基二硅胺烷对TiO2纳米管阵列进行低表面能处理,得到超疏水表面．用接触角测量仪测定表面疏水性,采用SEM、EDS技术研究改性前后试样表面的形貌和元素组成,并利用极化曲线和电化学阻抗谱法研究了超疏水膜的耐腐蚀性能．结果表明,TiO2纳米管阵列经改性后超疏水效果明显,耐腐蚀性能大幅度提高．     

Controlling the particle size of nanobrookite TiO2 thin films

In this study, pure nanobrookite TiO₂ thin films were successfully deposited on glass substrates with the spin-coating method using titanium butoxide and acetic acid. The particle size of TiO₂ films was controlled by the water:AcAc volume ratio. This study shows that it is possible to obtain single oriented pure brookite films. The structural and optical properties of the nanobrookite TiO₂ thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), spectrophotometer (NKD), and Fourier transform infrared spectrometer (FTIR).     

Synthesis of CeO2/TiO2 nanoparticles by laser ablation of Ti target in cerium (III) nitrate hexahydrate (Ce(NO3)3·6H2O) aqueous solution

A new synthesis process, laser ablation in an aqueous solution of target material, was applied to synthesize nanostructured CeO₂/TiO₂ catalyst particles. Reactivity within the laser plume (plasma) can be used to synthesize CeO₂ from an aqueous solution, 2 M cerium (III) nitrate hexahydrate (Ce(NO₃)₃·6H₂O) aqueous solution, and to fabricate TiO₂ from Ti target. CeO₂/TiO₂ nanoparticles were successfully synthesized by the laser ablation of Ti target in 2 M cerium (III) nitrate hexahydrate (Ce(NO₃)₃·6H₂O) aqueous solution. Laser ablation of Ti in a liquid environment and chemical reactions of the solution within a plasma plume are discussed.