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.     

La3＋-doped SrBi2Ta209 thin films for FRAM synthesized by sol-gel method

This paper discusses the possibility of synthesis of SBTL sol-gel films for use as active layers for non-volatile memory （FRAM）. La-doped SrBi2Ta209 thin films were synthesized by sol-gel method on Pt/TiO2/BPSG/SiO2/Si substrates. The structural features of the surface （AFM）, crystallization behavior （XRD） during the heating and ferroelectric properties of synthesized films were discussed. It was shown that an optimum surface structure and a high share of perovskite phase of SBTL-films were compared to SBT-films （Theating=800 ℃）. Achieved ferroelectric parameters suggested the possibility of using synthesized SBTL sol-gel films in non-volatile memory devices.     

Grain Size and Wettability of TiO2/SiO2 Photocatalytic Composite Thin Films

The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal, increase the hydroxyl content on the surface of TiO2 films, lower the contact angle for water on TiO2 films and enhance the hydrophilic property of TiO2 films. The super-hydrophilic TiO2/SiO2 photocatalytic composite thin films with the contact angle of 0-° are obtained by the addition of 10%-20% SiO2 in mole fraction.     

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.     

La-doped SnO2 synthesis and its electrochemical property

Tin dioxide (SnO₂) and La-doped (1%, 5%, 10% in mass ratio) SnO₂ samples were prepared via a hydrothermal method. The as-prepared powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results showed that the particle size of SnO₂ decreased gradually with the increase of the doped La element. When used as anode materials of Li ion battery, the La-doped samples exhibited better cycling performance than the pure SnO₂, and the cycling performance of the La-doped samples got better and better with the increase of the doped La. The better electrochemical performance of the doped material could be attributed to the doping of La element, which not only enabled SnO₂ powders to have a good dispersivity but also reduced their particle size.     

A stable and efficient La-doped MIL-53(Al)/ZnO photocatalyst for sulfamethazine degradation

Photocatalytic technology can solve various environmental pollution problems, especially antibiotic pollution. A novel La-doped MIL-53(Al)/ZnO composite material was successfully synthesized by a combination of hydrothermal method and calcination, showing high photocatalytic degradation percent of sulfamethazine (SMT). The 2 mol% La MIL-53(Al)/ZnO photocatalyst shows the highest degradation efficiency toward SMT (92%) within 120 min, which is 4.1 times higher than pure ZnO (increased from 18% to 92%). In addition, the degradation analysis of SMT by high performance liquid chromatography proves that the products are CO₂ and H₂O. The improved photocatalytic activity is mostly caused by the following factors. (1) Doping La ions can decrease the band gap of ZnO, enhance light response, and effectively enhance the separation rate of photo-generated holes and electrons. (2) MIL-53(Al) can adsorb SMT and promote the separation of electron. This work shows that the synthesized La-doped MIL-53(Al)/ZnO photocatalyst is expected to be used as a green and effective method for treatment of environment water pollution.     

Humidity sensing properties of La~(3+)/Ce~(3+)-doped TiO_2-20 wt.% SnO_2 thin films derived from sol-gel method

The humidity sensing properties of La3+/Ce3+-doped TiO2-20 wt.%SnO2 thin films were studied.Sol-gel method was employed to prepare the films on alumina substrates.By constructing a humidity-impedance measuring system,the sensing behaviors were inspected for the films sintered at different temperatures.Experimental results showed that,0.5 wt.% of La2O3 or Ce2O3 doped films sintered at 500 °C for 2 h had the best humidity sensing properties,the impedance decreasing from 109 ? to below 104 ? in the humidity range of 15-95 RH%.Moreover,Ce3+-doping had better humidity sensing properties than La3+-doping.The doping mechanism was discussed in terms of phase composition,granularity of crystalline and segregation of rare earth ions at grain boundaries.     

High photocatalytic activity over starfish-like La-doped ZnO/SiO_2 photocatalyst for malachite green degradation under visible light

In this work,the unique starlike La-doped ZnO-SiO2 photocatalysts were constructed by an evaporation and calcination method and characterized in detail.UV-vis reflectance and DFT calculation confirm that the doping with La allows to obtain a decrease of band gap of ZnO/SiO_2,which enhances visible light absorbance and oxidizing ability.The photoluminescence intensity reduces greatly,indicating more effective separation of the photo generated carriers of La-doped ZnO-SiO2.Photocatalytic activities of Ladoped ZnO-SiO2 with different doping ratios under simulated visible light irradiation were evaluated with malachite green(MG) as a model pollutant.Under optimized conditions including solution pH of 8,15 mg/L of MG solution and 15 mg of catalyst dosage,0.2% La-ZnO-SiO2 exhibits the best catalytic activity in photodegradations of MG in water.The removal and mineralization efficiency of MG can reach 96.1%and 70.9% in 140 min,respectively.The as-prepared catalysts present superior stability and recyclability after four times reuse.Moreover,selective quenching experiments indicate that hydroxyl radical(·OH),hole(h~+) and superoxide radical(·O_2~-) are the main reactive species responsible for MG degradation.Possible mechanism for photocatalytic elimination of MG over La-doped ZnO/SiO_2 photocatalyst is finally proposed.     

Significantly improved high k dielectric performance: Rare earth oxide as a passivation layer laminated with TiO2 film

In order to achieve a super gate dielectric performance,rare earth oxides featuring for large band gap,good thermodynamic stability and relatively high k value were selected to be laminated with TiO₂ film to prepare bilayer dielectric films.As an example,the microstructure,morphology,band gap structure and electrical performance of TiO₂-Y₂O₃ bilayer films were systematically investigated.Results show that stacking sequence of TiO₂ and Y_...     

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.     

Preparation and characterization of gelatin/cerium(III) film

A novel gelatin film with antibacterial activity was prepared by electrostatic crosslinking using cerium (III) nitrate hexahydrate as the crosslinking agent. The structure and properties of the films were investigated by Fourier transform infrared spectra, tensile tests, thermogravimetric analysis, static drop contact angle and disc diffusion method. The results showed that cross-linking could not only improve the thermal and mechanical properties and lower the hydrophilic property of the films, but also make them exhibit strong antibacterial activity against Escherichia coli.     

Fabrication of low-resistance LaNi_xO_(3+δ) thin films for ferroelectric device electrodes

LaNiO_3 thin films with different La/Ni ratios were deposited on Si substrates by sol-gel process. The electrical resistivities of LaNi_xO_(3+δ) films with different La/Ni ratios were measured by four-probe method.LaNi_(0.95)O_(3+δ) thin film has the lowest resistivity. First-principle calculations show that LaNi_(0.95)O_(3+δ) has the largest Ni-O-Ni bond angle and the shortest Ni-O bond length, which means LaNi_(0.95)O_(3+δ) has the strongest metallic property, hence, the electrical resistivity is the lowest. Au/PZT(PbZr_(0.52)Ti_(0.48)O_3)/LaNi_xO_(3+δ) and Au/PZT/Pt ferroelectric capacitors were fabricated to evaluate LaNi_xO_(3+δ) as a bottom electrode. It is shown that fatigue properties of PZT films can be significantly improved by using LaNi_xO_(3+δ) instead of Pt as the bottom electrode. The Ⅰ-Ⅴ test results of PZT films show that LaNi_(0.95)O_(3+δ) as bottom electrode can reduce the threshold voltages of PZT films, suggesting that La/Ni ratio in LaNi_xO_(3+δ)has a large influence on the film properties.     

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.     

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.     

Novel self-assembled films of La-based phosphonate 3-aminopropyltriethoxysilane

Silane coupling reagent (3-aminopropyltriethoxysilane (APTES)) was prepared on single-crystal silicon substrates to form two-dimensional self-assembled monolayer (SAM). The terminal-NH2 groups in the film were in situ phosphorylated to-PO(OH)2 group to endow the film with good chemisorption ability. Then La-based thin films were deposited on phosphorylated APTES-SAM in order to make good use of the chemisorption ability of-PO(OH)2 groups. The thickness of the film was determined with ellipsometer, while phase trans-formation and surface morphology, surface energy, phase composition were analyzed by means of atomic force microscope (AFM), contact angle measurements and X-ray photoelectron spectroscopy (XPS). The results indicated that the terminal -NH2 groups could be completely transformed into desirable-PO(OH)2 groups after phosphorylation of APTES-SAM. Detailed XPS analysis of the La3+ peaks revealed that lanthanum element existed in the films in different states. As a result, conclusion could be made that lanthanum reacted with-PO(OH)2 groups on the surface of the substrate by chemical bond which would improve the bonding strength between the film and silicon substrate.Since the La-based thin films were well adhered to the silicon substrate, it might find promising application in the surface-modification of single-crystal Si and SiC in microelectromechanical systems (MEMS).     

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.     

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.     

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.     

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.     

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.