Photocatalytic Activity of Lanthanum and Sulfur Co-doped TiO_2 Photocatalyst under Visible Light

A novel lanthanum and sulfur co-doped TiO2 photocatalyst was synthesized by precipitation- dipping method, and characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM） and UV-Vis diffuse reflectance spectroscopy. Compared with the S-doped TiO, La-doped TiO2 and the standard Degussa P25 photocatalysts, the lanthanum and sulfur co-doped TiO2 photocatalyst （the molar percentage of La is 3.0%） calcined at 450 ℃ for 2 h showed the strongest absorption for visible light and highest activities for degradation of reactive blue 19 dye in aqueous solution under visible light（λ〉400 nm） irradiation. It was also discovered that the co-doping of lanthanum and sulfur hindered the aggregation and growth of TiO2 particles, and the doping of lanthanum reduced slightly the phase transition temperature ofTiO2 from anatase to rutile.

Structure, photocatalytic and antibacterial activity study of Meso porous Ni and S co-doped TiO2 nano material under visible light irradiation

Undoped and Ni–S co-doped mesoporous TiO2 nano materials were synthesized by using sol–gel method.The characteristic features of as prepared catalyst samples were investigated using various advanced spectroscopic and analytical techniques.The characterization results of the samples revealed that all the samples exhibited anatase phase(XRD),decreasing band gap(2.68 eV)(UV–Vis-DRS),small particle size(9.2 nm)(TEM),high surface area(142.156 m^2·g^-1)(BET),particles with spherical shape and smooth morphology(SEM);there is a frequency shift observed for co-doped sample(FT-IR)and the elemental composition electronic states and position of the doped elements(Ni and S)in the TiO2 lattice analyzed by XPS and EDX.These results supported the photocatalytic degradation of Bismarck Brown Red(BBR)achieved with in 110 min and also exhibited the antibacterial activity on Staphylococcus aureus(MTCC-3160),Pseudomonas fluorescence(MTCC-1688)under visible light irradiation.

Preparation and Photocatalytic Activity of Ce, H3PW12O40 co-doped TiO2 Hollow Fibers

A series of Ce, H3PW12O40 co-doped TiO2 hollow fibers photocatalysts have been prepared by sol-gel method using ammonium ceric nitrate, H3PW12O40 and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500 ℃ in N2 atmosphere for 2 h. Scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption mea- surements, and UV-Vis spectroscopy are employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photo- catalytic performance of the samples has been studied by photodegradation phenol in water under UV and visible light irradiation. The results show that the TiO2 fiber materials have hollow structures, and the co-doped TiO2 hollow fibers exhibit higher photocatalytic activities for the degradation of phenol than un-doped, single-doped TiO2 hollow fibers under UV and visible light. In addition, the recyclability of co-doped TiO2 fibers is also confirmed that the TiO2 fiber retains ca. 90% of its activity after being used four times. It is shown that the co-doped TiO2 fibers can be activated by visible light and may be potentially applied to the treatment of water contaminated by organic pollutants. The synergistic effect of Ce and H3PW12O40 co-doping plays an important role in improving the photocatalytic activity.

Low Pressure Chemical Vapor Deposition of Nb and F Co-Doped TiO₂Layer

Nb and F co-doped anatase TiO2 layers were deposited by low pressure chemical vapor deposition (LPCVD) at pressure of 3 mtorr using titanium-tetra-iso-propoxide (TTIP), O2 and NbF5 as precursor, oxidant and dopant respectively. Resistivity beyond 100 Ωcm for undoped layer was decreased with increasing supply of the dopant and dependent on the supply ratio of O2 to TTIP and decreased to 0.2 Ωcm by the optimization. X-ray fluorescent spectroscopy showed Nb-content in the layer was decreased with the O2-supply ratio. X-ray photo-spectroscopy indicated that F substituted O-site in TiO2 by O2-supply but carbon-contamination and F missing substitution in the O-site were significantly increased by excess O2-supply. Further, it was suggested that the substituted F played an important role to reduce resistivity without significant contribution of O-vacancies. XRD spectra showed F missing substitution in the O-site degraded the crystallinity.

V-Ga共掺TiO_2光伏电池模拟与研究

基于实验上获得的带隙宽度为1.6eV的V-Ga共掺杂TiO2材料,设计了一种新型pin结构光伏电池.通过Nb:TiO2作为n型重掺杂层,Cu2O或CuO作为p型掺杂层,建立pn结自建电场.中间层V-Ga:TiO2为主要光吸收层,运用AMPS-1D软件模拟器件性能,研究Cu2O或CuO材料作为p型层对光伏性能的影响.模拟结果显示,Cu2O在这种结构中适合作为p型层,优化后器件光伏转化效率可达到34%.此外,通过对材料中带尾缺陷密度、吸收层与p型层界面对器件性能影响的研究,为器件制备中可能存在的问题提供解决思路.

Photocatalytic degradation of coking wastewater by nanocrystalline (Fe,N) co-doped TiO_2 powders

The yellowish nitrogen and iron co-doped nanocrystalline titanium dioxide ((Fe,N) co-doped TiO2) powders have been prepared by hydrothermal method using TiOSO4 and CO(NH2)2 as starting materials.The grain size of the synthesized powders was estimated as 11 nm by Scherrer's method.The UV-Vis diffuse reflectance spectra indicated that the light absorption edge of the powders was red-shifted up to 605 nm.And the doped TiO2 powders exhibited good photocatalytic activities during the photo-degradation of coking wastewater under sunshine irradiation.The biotreatability of the coking wasterwater after photocatalytic degradation was improved greatly and it is more suitable to be further treated by biochemical method.

Y/Eu co-doped TiO_2: synthesis and photocatalytic activities under UV-light

Y and Eu co-doped nano-TiO2 photocatalysts were successfully prepared via a sol-gel method and characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM）, ultraviolet-visible spectrophotometry（UV-vis）, photoluminescence（PL） and Fourier transform infrared（FT-IR） spectra. Experimental results indicated that Y and Eu doping inhibited the growth of crystalline size and the transformation from anatase to rutile phase and had the function of reducing particle reunion. At the same time, co-doping could also enhance the absorption in visible region and then narrowed the band gap. The photocatalytic activities of the samples were evaluated by the degradation of methylene blue（MB） under ultraviolet（UV） light irradiation, which showed much enhanced photocatalytic activities over un-doped TiO2. The degradation rate of 1.5% Y/Eu-TiO2 of methylene blue was 86%, which was about 5 times of that of un-doped TiO2, and the possible reasons for the improvement of photocatalytic activities were analyzed. In this experiment, the dopant amount of rare earth was 1.5% and the ratio of Y：Eu was 2：3 for the maximum photocatalytic degradation, and the sample calcined at 500℃ showed the best reactivity. For the best samples above, the removal rate of phenol under visble light was 53% whthin 2 h.

Existence form of lathanum and its improving mechanism of visible-light-driven La-F co-doped TiO2

The existence form and effect of La on the phase composition,morphology,recombination of photocarriers,and optical absorptivity of La-F codoped TiO2 were investigated.Experimental results indicate that all the phase composition of samples is anatase TiO2,the grain sizes decrease with the increasing of La content The catalysts have a well-defined spherical structure with an average size of 12-14 nm,and the doping elements are uniformly dispersed.Compared with pure TiO2,the absorption edge of La1.5F5-TiO2 red shifts from 388 to 437 nm,accordingly the energy gap(Eg) reduces from 32 to 2.84 eV,Besides,the recombination rate of electron-holes in La1.5F5-TiO2 is the weakest among the prepared samples,and the specific surface area of La1.5F5-TiO2 reaches 105.27 m2/g.The apparent reaction rate constant k of La1.5F5-TiO2 for methylene blue(MB) degradation under visible light obtained from the apparent first-order model achieves 0.0166±0.52 min-1,which is greater than 0.0033±0.09 min 1 of TiO2.Moreover,high-resolution transmission electron microscopy(HRTEM) observation reveals that there coexist La2O3 particles in the co-doped TiO2.

Zn and Ag Co-doped Anti-microbial TiO_2 Coatings on Ti by Micro-arc Oxidation

Micro-porous TiO2 coatings co-doped with Zn^2＋ and Ag nanoparticles were fabricated on Ti by microarc oxidation （MAO） for 0.5, 1.5, 2 and 4 min, respectively. The evolutions of morphology and phase component of the coating as a function of processing time were investigated. The microstructure of the 2 min treated coating was further observed by transmission electron microscopy to explore the coating formation mechanism. The amounts of Ag and Zn released from the 2 min treated coating were measured and the antibacterial properties of the coatings against Staphylococcus aureus （S. aureus） were also investigated. The obtained results showed that with prolonged MAO time, the contents of Ag and Zn on the coating surfaces increased. All the coatings were micro-porous with pore diameters of 1 -4μm; however, some pores were blocked by deposits on the 4 min treated coating. The 2 rain treated coating was composed of amorphous TiO2, anatase, futile, ZnO, Zn2TiO4 and homogenously distributed Ag nanoparticles. After immersion, Zn^2＋, Ag^＋, Ti^2＋ and Ca^2＋ were released from the coating and with the immersion time prolonged, the accumulated concentrations of these ions increased. After immersion for 36 weeks, the accumulated Zn2. and Ag^＋ concentrations were 6.88 and 0.684 ppm, respectively, which are higher than the minimal inhibitory concentration but much lower than the cytotoxic concentration. Compared with polished Ti control, the coatings co-doped with Zn^2＋ and Ag nanoparticles significantly inhibited the ad- hesions of S. uureus and reduced the amounts of planktonic bacteria in culture medium, indicating that the Zn and Ag co-doped TiO2 could be a bio-adaptable coating for long-lasting anti-microbial performance.

Visible light-driven photocatalysis of W,N co-doped TiO_2

W, N co-doped TiO2 nanoparticles were synthesized by a sol-gel method. The prepared samples were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FE-SEM）, trans- mission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FT-1R）, X-ray photoelectron spectroscopy （XPS） and diffuse reflectance spectrophotometry （DRS）. The results showed that the co- doped photocatalysts were essentially uniform spherical particles with the smallest particle size of 22.5 nm. Compared to un-doped TiO2, N-TiO2 and P-25, the absorption edge of the W, N co-doped TiO2 shifted to longer wavelength and its photocatalytic activity for degradation of methyl orange （MO） under Xe-lamp （350W） was higher.

Preparation, characterization and antibacterial properties of cobalt doped titania nanomaterials

Cobalt-doped titania(Co-TiO2)nanomaterials were synthesized by the sol–gel method at different calcination temperatures.Using Escherichia coli(a),Staphylococcus aureus(b)and Candida albicans(c)as target strains,the antibacterial activity in visible light of the nanomaterials were studied.Co-TiO2 nanomaterials were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),UV–Vis diffuse reflectance spectroscopy(DRS),Fourier transform infrared spectrum(FT-IR)and X-ray photoelectron spectroscopy(XPS).The Co ions in the Co-TiO2 nanomaterial exist in the form of CoTiO3 phase.The antibacterial properties of Co-TiO2 nanomaterials on E.coli(a),S.aureus(b)and C.albicans(c)were investigated with the oscillating flask method and the inhibition zone method.The nanomaterials calcined at 600°C exhibit excellent antibacterial activity.The bacteriostatic rates for E.coli,S.aureus and C.albicans reached 99.5%,91.3%and 93.4%respectively.The diameters of the antibacterial rings were up to 36 mm,37 mm,30 mm respectively,and the clarity of the ring was clear.The antibacterial properties of Co-TiO2 nanomaterials were compared with those of traditional silver sol,zinc oxide sol and Zn-doped TiO2 nanomaterials The mechanism of the influences of Co ions doping on the antibacterial activity of TiO2 nanomaterials was also discussed.The doping of Co ions inhibits the particle size of the antibacterial agent and extends the photocatalytic response range,thereby improving the photocatalytic performance of the antibacterial agent.

Effect of Ge–GeO_2 co-doping on non-ohmic behaviour of TiO_2–V_2O_5–Y_2O_3 varistor ceramics

An investigation was made into the effect of doping with the elemental crystal Ge or/and GeO2 on the TiO2-V2O5-Y2O3 varistor ceramics. The result shows that as the doping contents of V2O5 and Y2O3 are 0.5 tool%, respectively, co-doping with 0.3 mol% Ge and 0.9 mol% GeO2 makes the highest α value （α = 12.8）, the lowest breakdown voltage Vlmg （VlmA = 15.8 V/ram） and the highest grain boundary barrier ФB （ФB = 1.48 eV）, which is remarkably superior to the TiO2-V2Os-Y203 varistor ceramics undoped with Ge and GeO2 and mono-doped with Ge or GeO2. The TiO2-V2Os-YEO3-Ge-GeO2 ceramic has the prospect of becoming a novel varistor ceramic with excellent electrical properties.