Effect of different doping elements on performance of Ce-Mn/TiO2 catalyst for low temperature denitration

Sm and Ho were doped in Ce-Mn/TiO₂ catalyst respectively to enhance its denitration performance at low temperature.X-ray diffraction(XRD),N₂ adsorption-desorption,X-ray photoelectron spectroscopy(XPS),NH₃-temperature programmed desorption(NH₃-TPD),H₂-temperature programmed reduction(H₂-TPR) and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) techniques were used to analyze the structure and performance ...     

Synthesis,characteristics, and antibacterial activity of a rare-earth samarium/silver/titanium dioxide inorganic nanomaterials

An inorganic nanomaterials combination of Sm, Ag, and TiO2 was synthesized using supercritical fluid drying （SCFD） combined with solgel techniques. The structure, photocatalysis and bacteriostatic activity of the materials were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, X-ray photoelectron spectroscopy （XRPS）, photocatalytic performance, and antibacterial activity experiments. The XRD results showed that the average particle diameter of Sm/Ag/TiO2 was 14.62 nm and Ag and Sm ions were dispersed on the surface of TiO2 in a highly dispersed, amorphous form. The TEM image showed that the size of the particle was 12 nm using the scherer formula. The XPS result showed that the element Sm was doped and Ag was loaded inorganic nanomaterials successfully. Sm/Ag/TiO2 exhibited optimal photocatalytic properties at 600 oC, the photocatalytic optimal proportion of Sm/Ag/TiO2 was 2：2：100. When the molar ratio was 2：2：100, the bacteriostatic circle diameter was 16 mm for Staphylococcus aureus, the minimum bacteriostatic concentration was 200μg/mL for white beads coccus, and the minimum bactericidal concentration was 2×10^4μg/mL for white beads coccus. The SEM results showed that the antibacterial material attached to the candida albicans cell surface, cells appeared fold deformation. Therefore the inorganic nanomaterials Sm/Ag/TiO2 had high temperature resistance, good photocatalytic and antibacterial characteristics in visible light.     

Preparation and photocatalytic activity of La^3＋ and Eu^3＋ co-doped TiO2 nanoparticles： photo-assisted degradation of methylene blue

Rare earth ions La³⁺ and Eu³⁺ co-doped TiO₂ photocatalyst (La-Eu/TiO₂) was prepared by sol-gel method, and characterized by various techniques such as X-ray diffraction (XRD), specific surface area and porosity (BET and BJH), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the La-Eu/TiO₂ was evaluated by the degradation of methylene blue (MB) under UV light irradiation. The catalyst had a relatively uniform particle diameter distribution in the range of 40–60 nm. When calcining at 600°C, the XRD patterns of La-Eu/TiO₂ indicated the anatase phase, while the XPS patterns showed the Ti⁴⁺, La³⁺ and Eu³⁺ ions existence. The DRS spectra showed red shift in the band-gap transition. The experimental results of MB degradation demonstrated that the photocatalytic activity of La-Eu/TiO₂ was significantly enhanced due to better separation of photogenerated electron-hole pairs.     

Hydrophilic and photocatalytic performances of lanthanum doped titanium dioxide thin films

Pure and La-doped TiO2 thin films were prepared on glass by sol-gel method using tetrabutyl titanate as Ti precursors. Their chemical composition, structure and properties were characterized by X-ray d...     

A comparative study of physicochemical and photocatalytic properties of visible light responsive Fe,Gd and P single and tri-doped TiO2 nanomaterials

High performance Fe-Gd-P tri-doped TiO_2 nanoparticles(1 at% for each dopant) were successfully synthesized by a modified sol-gel method. Various analytical and spectroscopic techniques were carried out to determine the physicochemical properties of the prepared samples, including XRD, EDX, FESEM,BET, FTIR, XPS, PL, EIS and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of prepared samples were evaluated by photo degradation of methyl orange(MO) and 4-chlorophenol(4-CP) as model pollutants under visible light irradiation. Effects of each dopant on different properties of TiO_2 nanoparticles were investigated. Results show that Gd and P doping enhances TiO2 surface textural properties by forming Ti-O-Gd and Ti-O-P bonds. It is found that Gd plays a superior role in increasing oxygen vacancies and organic species on TiO_2 surface. Gd doping also facilitates transferring of the photo-induced charge carriers to the surface adsorbed species. The enhanced electronic band structure and visible light response, as well as high electron lifetime of Fe-Gd-P tri-doped sample is mainly attributed to Fe and Gd doping. The tri-doped TiO_2 with rate constant of k_(app)= 1.28 × 10~(-2) min~(-1) for MO and k_(app) = 0.94 × 10~(-2) min~(-1) for 4-CP, shows the highest photodegradation rate among all samples including undoped and single doped samples. The improved photocatalytic performance of Fe-Gd-P tridoped TiO_2 is due to the synergistic effect of enhanced surface chemistry and textural properties,increased number of surface adsorbed hydroxyl groups and organic species, improved visible light absorption, increased lifetime of the photo-induced electron/hole pairs and boosted interfacial charge transfer.     

Photocatalytic reduction of CO2 over Sm-doped TiO2 nanoparticles

Highly efficient photocatalytic reduction of CO₂ is essential for solving the greenhouse effect and energy crisis. In this paper, the Sm-TiO₂ nanocomposites were successfully prepared via sol-gel method. The CO₂ photoreduction activities of synthesized samples were tested under irradiation for 6 h and the results indicate that the 0.5% Sm-TiO₂ catalyst has superior performance and stability. The CO and CH₄ yields of 0.5% Sm-TiO₂ catalyst are 55.47 and 3.82 μmol/g·cat respectively, which are 5.02 and 2.67 times the yield of TiO₂. The possible mechanism of Sm doped TiO₂ was investigated through comprehensive characterization and photoelectrochemical analysis. After the Sm doping, the photo-generated electrons in TiO₂ could migrate to Sm 4f, and some of them can be captured by reducing Sm³⁺ to Sm²⁺, which can lower the recombination rate of electron and hole pairs. Therefore, the enhanced photocatalytic performance could be ascribed to large specific surface area, fast separation rate of electron–hole pairs and high visible light response. This report provides some meaningful attempts in researching the CO₂ photocatalytic reduction.     

Enhanced visible light photoactivity of TiO2/SnO2 films by tridoping with Y/F/Ag ions

The Y, F, and Ag tridoped TiO₂/SnO₂ composite nanocrystalline film (YFAg–TS) with prominent photocatalytic performance was prepared by the modified sol–gel method and was characterized by utilizing X-ray diffraction (XRD), differential thermal and thermogravimetric (DTA–TG) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method, ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), and photoluminescence (PL). The XRD and DTA–TG results expose that the YFAg–TS catalyst is a mixed phase consisting of anatase, rutile, and chlorargyrite, which is beneficial to improving the photocatalytic performance of TiO₂. The SEM, TEM, and BET results disclose that the YFAg–TS film has smaller nanoparticles, higher specific surface area, and narrower pore size compared with pure TiO₂ film. The XRD and TEM results exhibit that a part of yttrium can enter the TiO₂ lattice to induce lattice distortion. The XPS results confirm the presence of Y³⁺ state in the YFAg–TS sample, and Y³⁺ ions can act as the trapping site of electrons to expedite the separation of electrons and holes. The UV–vis DRS results reveal that the YFAg–TS film has an obvious absorption edge shift and a narrower bandgap (2.70 eV) compared with pure TiO₂ film. The PL results show that the YFAg–TS film has the highest photogenerated electrons and holes separation efficiency and charges transfer efficiency among all samples. The photocatalytic activity of the YFAg–TS was assessed by monitoring the degradation of methyl green and formaldehyde solution. The results manifest that the YFAg–TS film has high stability and excellent photocatalytic performance. The possible synergistic photocatalytic mechanism of YFAg–TS films has been discussed in this paper.     

Photocatalytic degradation of imidacloprid by composite catalysts H3PW12O40/La-TiO2

A series of La-doped TiO2 with different mass fractions were prepared by sol-gel method. Composite catalysts H3PW12O40/La-TiO2 with different loading levels were synthesized using impregnation method. The prepared samples were characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy (DRS) and nitrogen adsorption-desorption analysis. The Keggin structure of H3PW12O40 (HPW) remained intact on the surface of the composites, they had relatively uniform spherical grains of diameter less than 20 nm. The visible light activity of prepared composites were improved by loading HPW and doping La. The prepared composites were used as photocatalysts in degradation of pesticide imidacloprid. Results revealed that 20%H3PW12O40/0.3%La-TiO2 possessed the best photocatalytic activity. Thus, the degradation conversion of imidacloprid reached 98.17% after 60 min irradiation when 20%H3PW12O40/0.3% La-TiO2 was used as catalysts. The degradation of imidacloprid corresponded with first-order kinetic reaction, and the half life of the degradation of imidacloprid was 9.35 min in the optimal conditions.     

Preparation and photocatalytic activity of Fe3O4@SiO2@ZnO:La

In this study, Fe₃O₄@SiO₂@ZnO:La microspheres were successfully prepared. The microspheres have the advantages of both ZnO doped with La and the Fe₃O₄@SiO₂ structure such that the former improves the photocatalytic activity of ZnO and the latter can be reused. The X-ray diffraction (XRD), a field emission scanning electron microscope (SEM), a field emission transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and a vibrating sample magnetometer (VSM) were used to characterize Fe₃O₄@SiO₂@ZnO:La microspheres. Methyl orange was used as the model molecule to study the effect of the Zn²⁺ concentration and the doping amount of La on the photocatalytic activity of Fe₃O₄@SiO₂@ZnO:La microspheres. Results show that in the synthesis of Fe₃O₄@SiO₂@ZnO:La microspheres, photocatalytic activity of the microspheres is enhanced first and weakened later with the increase of Zn²⁺ concentration. In the La doping process, the photocatalytic activity of Fe₃O₄@SiO₂@ZnO:La microspheres is enhanced with the increase in the La doping amount. The magnetic photocatalysts not only have high photocatalytic activity, but also can be reused. After being reused five times, the photocatalyst's degradation rate of methyl orange is still as high as 81%, which shows that magnetic photocatalysts have prospective wider applications in photocatalytic degradation of dye wastewater.     

Lanthanum and boron co-doped BiVO4 with enhanced visible light photocatalytic activity for degradation of methyl orange

BiVO4 photocatalysts co-doped with La and B were prepared by sol-gel method using citric acid as chelate.The samples were characterized by X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),scanning electron microscopy(SEM),Brumauer-Emmett-Teller(BET),UV-Vis diffuse reflectance spectra(DRS) and the photocatalytic activity was investigated by photocatalytic degradation of methyl orange(MO).The results showed that boron and lanthanum ions incorporated into the lattice of BiVO4,and co-doping led to more surface oxygen vacancies,high specific surface areas,small crystallite size,narrow band gap and intense light absorbance in visible region.And the doped La(III) ions could help the separation of photogenerated electrons.Compared with BiVO4 and B-BiVO4,the photocatalytic activity of La-B co-doped BiVO4 was remarkably improved due to the synergistic effects of the co-doped ions.The degradation rate of MO in 60 min was 98.4% when La doping content was 0.05 mol.%,which was much higher than that of pure BiVO4(20%) and B-BiVO4(37%).     

Preparation of La MnO_3/graphene thin films and their photocatalytic activity

A novel photocatalyst of La MnO3/graphene thin films with the perovskite-type was synthesized by sol-gel process assisted with spin-coating methods on glass substrates.The prepared samples were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), Brumauer-Emmett-Teller(BET) surface area analyzer, X-ray photoelectron spectroscopy(XPS) and UV-vis diffuse reflectance spectroscopy.Results showed that after the introduction of graphene, the perovskite structure was unchanged and the size of La MnO3 particles was about 22 nm, which uniformed growth in graphene sheet.Determination of contact angle indicated that the contact angle of glass substrate decreased and the hydrophilicity improved after treating with H2SO4 and APTES.The UV-Vis photocatalytic activity of the photocatalysts was evaluated by the degradation of diamine green B.La MnO3/graphene thin films had better photocatalytic ability than La MnO3 and Ti O2 films.The obtained k was 0.5627 and 0.3441 h–1 corresponding to La MnO3/graphene films and Ti O2 films, respectively.     

Luminescent characterization of rare earth Dy3+ ion doped TiO2 prepared by simple chemical co-precipitation method

Pure and rare-earth ion (Dy³⁺) doped TiO₂ nanomaterials were prepared through a chemical co-precipitation method. The chemical composition, microstructure and optical properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-visible spectroscopy and photoluminescence (PL). XPS analysis reveals that Dy³⁺ ions are preferentially occupied in the TiO₂ crystallite lattices. Both the XRD and TEM analyses confirm that both the pure and Dy doped TiO₂ are in pure anatase phase and in nano size range, respectively. Also it is found that the maximum solubility limit for Dy³⁺ ions is found to be 0.4% in TiO₂ matrix, above which it occupies interstitials and/or crystallite surface of TiO₂ nanocrystals. From the UV-Vis spectroscopy studies it is found that Dy doping induces blue shift in TiO₂. From the PL analysis it is found that doping Dy³⁺ improves the luminescence behavior in comparison with the pure TiO₂ nanoparticles. Overall, doping very low concentrations of Dy³⁺ greatly alters the structural morphology and directly increases the luminescence behavior of TiO₂ suitable for advanced optoelectronic applications.     

Effect of Tb2O3 additive on structure of anatase and photocatalytic activity of TiO2/（O′＋β′）-Sialon multi-phase ceramics

Effect of rare earth oxide Tb₂O₃ additive on transformation behavior and grain growth of anatase and photocatalytic activity for TiO₂/(O′ +β′)-Sialon multi-phase ceramic was investigated and the mechanism was discussed. X-ray diffractometer (XRD) was employed for the analysis of phase composition, grain size and lattice parameters of anatase. Photocatalytic activity of the composites was investigated through its photocatalytic degradation to methylene blue (MB) solution. The results showed that Tb₂O₃ significantly inhibited the transformation process, which displayed an appreciably intensified effect with increasing Tb₂O₃ content. It could be attributed to the coaction of the active and passive influence mechanisms. For Tb³⁺ entering TiO₂ lattice, replacing Ti⁴⁺ accelerated the transformation, whereas the lattice distortion caused by it was unfavorable for the process. On the other hand, the redox reaction between Tb³⁺ and TiO₂ as well as the Tb₂O₃ deposited on the surface of TiO₂ inhibited the transformation. The addition of Tb₂O₃ effectively restrained the grain growth of TiO₂ and the effect became significant with the increase of its content. With the increase of Tb₂O₃ addition, the photocatalytic activity of the catalysts increased and then dropped after reaching the maximum at about 2%. The action mechanism of Tb₂O₃ could be attributed to its optical properties and its effect on phase transformation, grain growth and crystal structure of TiO₂.     

Electronic properties and photodegradation ability of Nd-TiO2 for phenol

In this study, the photocatalytic activity of Nd-TiO₂ photocatalysts obtained by common hydrothermal method was evaluated by practical experiments and theoretical calculations based on density functional theory (DFT). The synthesized photocatalysts were characterized by X-ray diffraction (XRD), N₂ adsorption–desorption, Fourier transform infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) to study their physical/chemical properties. At the same time, the photoelectronic performance was also investigated. The photodegradation ability of as-prepared photocatalysts and the effect of Nd doped amount and photocatalysts dosage were investigated by the photodegradation of phenol (30 mg/L) under 400 W metal halide lamp (UV–Vis). The effect of Nd on electronic properties of TiO₂ and adsorption ability of phenol were discussed. Results show the red-shift wavelength of 0.5 mol%Nd-TiO₂, indicating that its absorption capacity is stronger than pristine TiO₂ in the same wavelength range. The result of DFT calculations demonstrates that the optical bandgap of Nd-TiO₂ is profoundly reduced, thus the light absorption ability is promoted, which will be responsible for the enhanced photocatalytic performance of Nd-TiO₂. 0.5 mol% Nd is an optimum value for photodegradation phenol, and phenol can be completely degraded by 0.5 mol%Nd-TiO₂ for 210 min, the higher catalytic performance is derived from the efficient separation of e^–/h⁺ pairs. Moreover, the adsorption energy calculations of phenol on TiO₂ (101) and Nd-TiO₂ (101) demonstrate that the Nd doping can significantly enhance the adsorption ability of phenol on catalyst surfaces because of the formation of Nd–O bonds. At last, the stability measurement through four recycles exhibits that 0.5 mol%Nd-TiO₂ possesses excellent stability.     

Enhanced photocatalytic activities of Nd-doped TiO_2 under visible light using a facile sol-gel method

Titanium dioxide nanoparticles modified with neodymium in the range of 1 mol% to 5 mol% were prepared with template-free sol-gel method.The structures of obtained samples were characterized by X-ray powder diffraction analysis.X-ray photoelectron spectroscopy,scanning electron microscopy,transmission electron microscopy and diffuse reflectance spectroscopy.The photocatalytic activity of the obtained samples was evaluated by photodegradation of methyl orange in aqueous solution under ultraviolet-visible(λ 350 nm) and visible(λ 420 nm) irradiation.The experimental results show that the 1 mol% Nd-doped TiO_2 exhibits the highest photocatalytic activity,of which the degradation can reach to 96.5% under visible irradiation.According to the XRD results,the pristine samples are combined with anatase TiO_2 and rutile TiO_2.while the Nd-doped TiO_2 samples are anatase TiO_2 only.This transformation has made an obvious promotion of photocatalyst activity after modification.     

Synergetic effect of thermo-photocatalytic oxidation of benzene on Pt-TiOe/Ce-MnOx

Pt-TiO2/Ce-MnOx catalysts were obtained by depositing TiO2 and platinum, respectively,on the Ce-Mn oxides prepared by co-precipitation method. The phases of CeO2 and anatase TiO2 were observed in the catalysts from X-ray diffraction (XRD) patterns. X-ray photoelectron spectroscopy (XPS) revealed that lattice oxygen and surface active oxygen were found to be the major components of O1s. The experiment results showed that the kinetic constant of thermo-photocatalysis was 7.6 times of the kinetic constant of single photocatalysis, and was 2.29 times of the kinetic constant sum of photocatalytic and thermal catalytic reaction.     

Effect of titanium dioxide and gadolinium dopants on photocatalytic behavior for acriflavine dye

Herein,we report the experimental methodology to optimize the operational parameters of the photocatalytic degradation of acriflavine dye using TiO_2 and Gd~(3+) as dopant.A series of Gd~(3+) doped TiO_2 nanoparticles were synthesized via hydrothermal route and characterized using various techniques like FT-IR,UV,XRD,FESEM and EDS.It is observed that synthesized particles are in the range of 25-30 nm with spherical shape in nature.TiO_2 has rutile phase and the average particle size was estimated from Scherrer's equation.Energy bandgap was estimated using Tauc's plot.The photodegradation was carried out under UV light in pseudofirst order condition.To understand the kinetics,four experimental parameters were chosen as independent variables like percentage of dopant,initial concentration of dye,dosage of catalyst and pH of reaction medium.The degradation efficiency of 92% was observed for 0.5%Gd doped TiO_2 at catalyst dosage of 0.3 g/dm~3,pH 10 and dye concentration of 3×10~(-6) mol/dm~3.It is observed that,the photocatalytic activity of TiO_2 can be increased by using gadolinium as dopant only in optimum concentration.Further,this photocatalyst can be employed to degrade other o rganic pollutants.     

Preparation, spectral characteristics and photocatalytic activity of Eu-doped WO3 nanoparticles

Eu³⁺-WO₃ nanoparticles were successfully prepared by the modified method of Pechini. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and UV-vis spectroscopy. Results showed that the Eu³⁺-WO₃ nanoparticles, which had an average external diameter of 10–25 nm, were composed of the different shapes of puncheon and catenary after being pretreated by pH, pressure vessal, and surfactant. Moreover, structural transformation matrix contained different crystals of anorthic and orthorhombic structure. The photocatalytic activities of the nanoparticles were evaluated by photocatalytic decomposition of rhodamine B. Eu³⁺-WO₃ nanoparticles were more efficient than WO₃ and TiO₂ on sunlight use ratio. Photocatalysis experiments indicated that the Eu³⁺-WO₃ nanoparticles exhibited the highest photocatalytic activity.     

Novel promoting effects of cerium on the activities of NO_x reduction by NH_3 over TiO_2-SiO_2-WO_3 monolith catalysts

A series of catalysts were prepared by doping different loadings of CeO2 over TiO2-SiO2-WO3 and used for the selective catalytic reduction of NOx by NH3. The experimental results showed that the selective catalytic reduction（SCR） performance and SO2-resistant ability of TiO2-SiO2-WO3 were greatly enhanced by the introduction of cerium. The catalyst containing 10% CeO2 showed the highest NO conversion in a wide temperature range and good N2 selectivity with broad operation temperature window at the gas hourly space velocity（GHSV） of 30000 h–1, which was a very promising catalyst for NOx abatement from diesel engine exhaust. The catalysts were characterized by X-ray diffraction（XRD）, scanning electron microscopy with energy dispersive X-ray spectroscopy（SEM-EDS）, N2 adsorption-desorption（BET） and X-ray photoelectron spectroscopy（XPS）. The characterization results showed that the bigger pore radius, higher surface atomic concentration and dispersion of Ce and the abundant adsorbed oxygen on the surface of catalyst contributed to the best NH3-SCR performance of CeO2/TiO2-SiO2-WO3 catalyst containing 10% CeO2.     

利用热喷涂技术制备二氧化钛光催化涂层研究现状与展望

纳米二氧化钛(TiO_2)因稳定、廉价、无毒等优势,成为研究与应用最广泛的光催化剂。为了解决颗粒状催化剂难以回收、易于造成二次污染等缺点,制备TiO_2涂层是较为理想的选择。热喷涂技术具有成本低、效率高、容易实现大面积制备等优势,在Ti O2涂层制备研究中得到广泛关注。基于此,本文综述了等离子喷涂、火焰喷涂、超音速火焰喷涂、冷喷涂技术在制备纳米TiO_2涂层方面的研究现状,并分析了影响TiO_2涂层光催化性能的关键制备因素,讨论了多种热喷涂技术在涂层微观结构控制与性能调控方面的研究现状,并对未来发展做了展望。