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.     

Effect of Ho-doping on photocatalytic activity of nanosized TiO2 catalyst

Ho-doped TiO2 nanoparticles with higher photocatalytic activity were prepared by an acid-catalyzed sol-gel method. The photocatalytic decomposition of methyl orange in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities. The effects of Ho doping on the crystallite sizes, crystal pattern, surface composition, and optical property of the catalysts were investigated by means of techniques such as X-Ray Diffraction （XRD）, Transmission Electron Microscopy （TEM）, Diffuse Reflectance UV-Vis Spectroscopy （UV-Vis DRS）, Fourier Transform Infrared （FT-IR）, and Photo-Luminiscence （PL） spectra. Moreover, the modification mechanism of Ho doping was also discussed. The results showed that Ho doping could inhibit phase transformation from anatase to rntile, suppress the growth of TiO2 grains, cause blue shift of the absorption spectrum edge, accelerate surface hydroxylation, and enhance the separation efficiency of photoinduced electron-hole pairs, which resulted in a significant improvement in the photoreactivity of Ho-doped TiO2. Among them, the Ho-doped TiO2 calcined at 500℃ achieved the highest photocatalytic activity.     

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.     

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.     

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.     

Facile synthesis of Ag/La2O2CO3 hierarchical micro/nanostructures for antibacterial activity and phosphate removal

In this study, hierarchical Ag/La₂O₂CO₃ micro/nanostructures (MNSs) were synthesized by in situ loading Ag nanoparticles (NPs) on the surface of the La₂O₂CO₃ MNSs. The prepared La₂O₂CO₃ MNSs present flower-like shape and can be tuned by the molar ratio of La (NO₃)₃ and CO(NH₂)₂. In the molar ratio of 1:2 to 1:55, the La₂O₂CO₃ MNSs mainly consist of polyhedral rods, irregular rods and irregular spindles and their size is about 10, 8 and 7 μm, respectively. After loading Ag NPs, the spindle-like Ag/La₂O₂CO₃ MNSs were used for phosphate removal and antibacterial activity. At the initial phosphate concentration of 20 mg/L, the removal rate is 59.6%. The Ag/La₂O₂CO₃ MNSs have significant antibacterial activity and their MIC values for S. aureus and E. coli are 31.3 and 15.6 μg/mL, respectively. The results indicate that Ag/La₂O₂CO₃ MNSs may have good application prospects in open water to inhibit bacterial growth.     

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 ...     

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.     

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.     

One-step solution combustion synthesis of micro-nano-scale porous Cu/CeO2 with enhanced photocatalytic properties

The Cu/CeO₂ nanoporous composite material was prepared via a one-step and energy-saving method of solution combustion synthesis(SCS).The phase composition,surface morphology and optical characteristics of Cu/CeO₂ were studied.The results show that the SCS products are composed of cubic fluorite CeO₂ and Cu.Due to the generation and escape of gas during the synthetic reaction,the SCS CeO₂ shows porous structure,in which the mesopores(diameter 10-17 nm) ...     

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...     

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.     

Influence of inorganic anions and organic additives on photocatalytic degradation of methyl orange with supported polyoxometalates as photocatalyst

A novel supported polyoxometalate(POM),phosphotungstic acid immobilized into yttrium-doped TiO2(HPW-Y-TiO2) nano photocatalyst was prepared via sol-gel and impregnation method.The samples were characterized using Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD) and N2 absorption-desorption analysis.The results showed that the supported POM exhibited Keggin structure and anatase phase with large BET surface area.The influences of inorganic anions and organic additives on the photocatalytic degradation of azo dye methyl orange with HPW-Y-TiO2 as photocatalyst under UV light(λ≥365 nm) were investigated.Results showed that inorganic anions Cl-,SO42-,CO32-and NO3-had inhibition effect on the degradation of methyl orange.A great enhancement of degradation rate was obtained while H2O2 and ethyl alcohol were applied.The degradation rates improved with the increase of H2O2 concentration.The optimum additive amount of ethyl alcohol was 0.5 mol/L.The possible mechanisms of the effects of additives on methyl orange degradation were discussed.     

Phase Evolution and Mechanical Properties of Nano-TiO2 Dispersed Zr-Based Alloys by Mechanical Alloying and Conventional Sintering

The present study deals with the synthesis of 1.0 to 2.0 wt pct nano-TiO₂ dispersed Zr-based alloy with nominal compositions 45.0Zr-30.0Fe-20.0Ni-5.0Mo (alloy A), 44.0Zr-30.0 Fe-20.0Ni-5.0Mo-1.0TiO₂ (alloy B), 44.0Zr-30.0Fe-20.0Ni-4.5Mo-1.5TiO₂ (alloy C), and 44.0Zr-30.0Fe-20.0Ni-4.0Mo-2.0TiO₂ (alloy D) by mechanical alloying and consolidation of the milled powders using 1 GPa uniaxial pressure for 5 minutes and conventional sintering at 1673 K (1400 °C). The microstructural and phase evolution during each stage of milling and the consolidated products were studied by X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM), and energy-dispersive spectroscopy. The particle size of the milled powder was also analyzed at systemic intervals during milling, and it showed a rapid decrease in particle size in the initial hours of milling. XRD analysis showed a fine crystallite size of 10 to 20 nm after 20 hours of milling and was confirmed by TEM. The recrystallization behavior of the milled powder was studied by differential scanning calorimetry. The hardness of the sintered Zr-based alloys was recorded in the range of 5.1 to 7.0 GPa, which is much higher than that of similar alloys, developed via the melting casting route.     

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.     

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.     

Fabrication of highly efficient heterostructured Ag-CeO2/g-C3N4 hybrid photocatalyst with enhanced visible-light photocatalytic activity

On the basis of hydrothermal synthesis of Ag-CeO₂ microspheres, Ag-CeO₂/g-C₃N₄ composite photocatalyst with heterostructure was prepared by simple solvent evaporation of Ag-CeO₂ and g-C₃N₄. To characterize the composition, structure, morphology and light absorption properties of the as-prepared Ag-CeO₂/g-C₃N₄ composites, XRD, FTIR XPS, SEM, TEM, PL, BET and UV-vis DRS were used, respectively. The as-prepared photocatalyst was subjected to photocatalytic degradation of pollutants, and the prepared composite material has excellent photocatalytic activity for photodegradation of methylene blue (MB). The research shows that the photocatalytic properties of Ag-CeO₂/g-C₃N₄ composites were related to the mass ratio of Ag-CeO₂ microspheres and g-C₃N₄ nanosheets. When the ratio of Ag-CeO₂ microspheres: g-C₃N₄ is 1:5, the composites have the highest photocatalytic activity, which was 9.6 and 3.3 times that of single Ag-CeO₂ and g-C₃N₄, respectively. The improvement of photocatalytic activity is attributed to the heterostructure between the composite materials and the addition of noble metal silver, and the degradation of methylene blue by the visible light irradiation material is greatly improved. Finally, an attempt was made to analyze the principle of photocatalytic degradation of pollutants in prepared materials.     

Regeneration of the deactivated TiO2-ZrO2-CeO2 /ATS catalyst for NH3-SCR of NOx in glass furnace

Larger amounts of alkalis, alkali earth metals and sulfides in flue gas from glass furnace were easier to deactivate selective catalytic reduction (SCR) catalyst compared to the flue gases from other stationary sources. Catalyst regeneration has been an emerging research topic for flue gas denitrification in glass furnace. Regeneration of the deactivated TiO2-ZrO2-CeO2 /Al2TiO 5 -TiO2-SiO2 (ATS) complex phase ceramics catalysts used for NH3 -SCR of NO x in glass furnace was studied in this work. Effects of regeneration methods, including washing with different aqueous solutions and sulfuric acid, thermal regeneration, thermal reduction regeneration, and thermal regeneration with SO2 , on catalytic performance were comparatively investigated. In comparison of catalytic activities between the catalysts before and after regeneration, results showed that washing was the most effective regeneration method, and the sulfuric acid concentration of the washing solution was an important factor. Washing time directly affected catalyst regeneration efficiency and catalyst life. The regenerated TiO2-ZrO2 -CeO2 /ATS catalyst regained more than 90% NO conversion after being washed with 10 wt.% H2SO4 for 30 min.     

Propranolol hydrochloride degradation using La@TiO2 functionalized with CMCD

Propranolol hydrochloride can be considered a persistent and bioaccumulative pharmaceutical in the environment. This drug and its by-products are potentially toxic and have adverse effects, since these compounds have been associated with endocrine-disrupting effects, reproductive deficiencies, embryo abnormalities and pericardial oedema. TiO₂–La 0.05%–carboxymethyl-β-cyclodextrin (CMCD) nanoparticles were successfully prepared by a simple two-step method, which consists of sonification and functionalization. The characterization analyses reveal that lanthanum is dispersed on the semiconductor surface, probably forming Ti–O–La bonds, which can induce oxygen vacancies and surface defects that effectively restrain the recombination of photogenerated electron/holes pairs. The efficiency of TiO₂–La 0.05%–CMCD samples in degradation of propranolol under UV-light irradiation is higher than that of pristine TiO₂ within 20 min reaction, probably due to complex formation between the β-blocker and the oligosaccharide, which allows us to propose a photocatalytic mechanism based on the formation of intermediates and competition of these compounds to the radicals and CMCD cavities.     

A novel process for fabricating electrical contact SnO<Subscript>2</Subscript>/Ag composites by reciprocating extrusion

Reciprocating extrusion combined with simple powder compaction was used to produce electrical contact SnO₂/Ag composites from Ag and SnO₂ powders with improved properties. The SnO₂ particles were uniformly dispersed in the Ag matrix after 20 passes of extrusion. The hardness of the composites increased with extrusion passes and leveled off after ten passes, whereas the electrical conductivity decreased slowly after five passes. The variation of the coefficient of thermal expansion with temperature revealed that SnO₂/Ag interface strength increased with extrusion passes and was greatest after 20 passes. The SnO₂/Ag composites with 20 passes showed the best electrical contact properties in which there was no mass loss through mass transfer from cathode to anode during the make-break erosion test at both low and high current conditions. On the other hand, SnO₂/Ag composites with one pass and commercial SnO₂-In₂O₃/Ag specimens had an apparent mass loss under the same condition. Electrical contact composites produced by the present method are promising in electrical contact applications in consideration of cost and performance.