scholarly journals Application of Reverse Micelle Sol–Gel Synthesis for Bulk Doping and Heteroatoms Surface Enrichment in Mo-Doped TiO2 Nanoparticles

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 937 ◽  
Author(s):  
Roberto Nasi ◽  
Serena Esposito ◽  
Francesca Freyria ◽  
Marco Armandi ◽  
Tanveer Gadhi ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Reverse Micelle ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Actual State ◽  
Test Reaction ◽  
Potential Measurement ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Mo Content

TiO2 nanoparticles containing 0.0, 1.0, 5.0, and 10.0 wt.% Mo were prepared by a reverse micelle template assisted sol–gel method allowing the dispersion of Mo atoms in the TiO2 matrix. Their textural and surface properties were characterized by means of X-ray powder diffraction, micro-Raman spectroscopy, N2 adsorption/desorption isotherms at −196 °C, energy dispersive X-ray analysis coupled to field emission scanning electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance UV–Vis spectroscopy, and ζ-potential measurement. The photocatalytic degradation of Rhodamine B (under visible light and low irradiance) in water was used as a test reaction as well. The ensemble of the obtained experimental results was analyzed in order to discover the actual state of Mo in the final materials, showing the occurrence of both bulk doping and Mo surface species, with progressive segregation of MoOx species occurring only at a higher Mo content.

scholarly journals Characterization of Photoactive Fe-TiO2 Lime Coatings for Building Protection: The Role of Iron Content

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1847 ◽  
Author(s):  
Chrysi Kapridaki ◽  
Nikolaos Xynidis ◽  
Eleftheria Vazgiouraki ◽  
Nikolaos Kallithrakas-Kontos ◽  
Pagona Maravelaki-Kalaitzaki
Keyword(s):  
Tio2 Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Visible Radiation ◽  
Edge Structure ◽  
Doped Tio2 ◽  
X Ray ◽  
Vis Spectroscopy

Iron-doped TiO2 nanoparticles, ranging in Fe concentrations from 0.05 up to 1.00% w/w, were synthesized through a simple sol-gel method. Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Ultraviolet-Visible (UV-Vis) spectroscopy, nitrogen adsorption−desorption isotherms, X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure spectroscopy (XANES) were used to characterize the synthesized nanoparticles. The characterization of the Fe-doped TiO2 nanoparticles revealed the predominant presence of anatase crystalline form, as well as the incorporation of the Fe3+ ions into the crystal lattice of TiO2. The photocatalytic assessment of the Fe-doped TiO2 nanoparticles indicated that the low iron doping titania (0.05 and 0.10% w/w) have a positive effect on the photocatalytic degradation of Methyl Orange under visible radiation. Moreover, FTIR monitoring of calcium hydroxide pastes enriched with low Fe-doped TiO2 revealed enhancement of carbonation at both early and later stages. Improved photocatalytic performance and increased lime carbonation, observed in lime coatings with low Fe-doped TiO2 admixtures, established them as invaluable contributors to the protection of the built environment.

Synthesis, Characterization and Photocatalytic Activity of Nb-Doped TiO2 Nanoparticles

2012 ◽  
Vol 455-456 ◽  
pp. 110-114 ◽  
Author(s):  
Xuan Dong Li ◽  
Xi Jiang Han ◽  
Wen Ying Wang ◽  
Xiao Hong Liu ◽  
Yan Wang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Doped Tio2 ◽  
X Ray ◽  
Vis Spectroscopy

Nb-doped TiO2 powders with different concentrations of Nb have been synthesized by a sol-gel method and characterized by a series of technologies including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. The photocatalytic activity of Nb-doped TiO2 is evaluated by degradation efficiency of methyl orange in aqueous solution. The results indicate that the photocatalytic activity of Nb-doped TiO2 synthesized with a Nb/Ti molar ratio of 5% is higher than that of TiO2 under the visible light.

Synthesis, Characterization and Photocatalytic Activity of Copper (II)-Doped Titanium Dioxide Powders

2011 ◽  
Vol 391-392 ◽  
pp. 728-731 ◽  
Author(s):  
Wen Churng Lin ◽  
Wein Duo Yang
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Specific Surface ◽  
Photoelectron Spectroscopy ◽  
Effective Means ◽  
Sol Gel ◽  
Particle Growth ◽  
X Ray ◽  
Surface Areas ◽  
Vis Spectroscopy

Different concentration of copper (II) doped TiO2 photocatalyst powders were synthesized through the sol-gel method and characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET)-specific surface area, transmission electron microscopy (TEM), and Ultraviolet–Visible (UV-Vis) spectroscopy. Cu2+-doping in the TiO2 promotes the particle growth, decreases the specific surface areas of powders, extends the absorption to visible light regions, and exhibits the vis-photocatalytic activity for methylene blue (MB) degradation. Appropriate content of Cu2+-doping is an effective means to improve the photocatalytic activity of TiO2 for MB degradation under visible light irradiation.

scholarly journals Physical Characteristics of Titania Nanofibers Synthesized by Sol-Gel and Electrospinning Techniques

2010 ◽  
Vol 5 (1) ◽  
pp. 155892501000500 ◽  
Author(s):  
Soo-Jin Park ◽  
Yong C. Kang ◽  
Ju Y. Park ◽  
Ed A. Evans ◽  
Rex D. Ramsier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Average Diameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Ceramic Nanofibers ◽  
Titania Nanofibers

Titania nanofibers were successfully synthesized by sol-gel coating of electrospun polymer nanofibers followed by calcining to form either the pure anatase or rutile phases. Characterization of these materials was carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy techniques. The average diameter of these ceramic nanofibers was observed to be around 200 nm for both the rutile and anatase forms. The valence band structure and optical absorption thresholds differ, however, indicating that nanofibrous mats of titania can be selectively developed for different applications in catalysis and photochemistry.

scholarly journals A Solvothermal Synthesis of TiO2 Nanoparticles in a Non-Polar Medium to Prepare Highly Stable Nanofluids with Improved Thermal Properties

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 816 ◽  
Author(s):  
Teresa Aguilar ◽  
Ivan Carrillo-Berdugo ◽  
Roberto Gómez-Villarejo ◽  
Juan Gallardo ◽  
Paloma Martínez-Merino ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Tio2 Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
High Stability ◽  
Chemical Properties ◽  
Heat Transfer Fluid ◽  
Promising Alternative ◽  
X Ray ◽  
Vis Spectroscopy

Nanofluids are systems with several interesting heat transfer applications, but it can be a challenge to obtain highly stable suspensions. One way to overcome this challenge is to create the appropriate conditions to disperse the nanomaterial in the fluid. However, when the heat transfer fluid used is a non-polar organic oil, there are complications due to the low polarity of this solvent. Therefore, this study introduces a method to synthesize TiO2 nanoparticles inside a non-polar fluid typically used in heat transfer applications. Nanoparticles produced were characterized for their structural and chemical properties using techniques such as X-ray Diffraction (XRD), Raman spectroscopy, Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The nanofluid showed a high stability, which was analyzed by means of UV-vis spectroscopy and by measuring its particle size and ζ potential. So, this nanofluid will have many possible applications. In this work, the use as heat transfer fluid was tested. In this sense, nanofluid also presented enhanced isobaric specific heat and thermal conductivity values with regard to the base fluid, which led to the heat transfer coefficient increasing by 14.4%. Thus, the nanofluid prepared could be a promising alternative to typical HTFs thanks to its improved thermal properties and high stability resulting from the synthesis procedure.

scholarly journals Colloidal and Deposited Products of the Interaction of Tetrachloroauric Acid with Hydrogen Selenide and Hydrogen Sulfide in Aqueous Solutions

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 492 ◽  
Author(s):  
Sergey Vorobyev ◽  
Maxim Likhatski ◽  
Alexander Romanchenko ◽  
Nikolai Maksimov ◽  
Sergey Zharkov ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Photoelectron Spectroscopy ◽  
Ex Situ ◽  
Supersaturated Solution ◽  
Hydrodynamic Diameter ◽  
Elemental Selenium ◽  
Potential Measurement ◽  
Gold Colloids ◽  
X Ray ◽  
Vis Spectroscopy

The reactions of aqueous gold complexes with H2Se and H2S are important for transportation and deposition of gold in nature and for synthesis of AuSe-based nanomaterials but are scantily understood. Here, we explored species formed at different proportions of HAuCl4, H2Se and H2S at room temperature using in situ UV-vis spectroscopy, dynamic light scattering (DLS), zeta-potential measurement and ex situ Transmission electron microscopy (TEM), electron diffraction, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Metal gold colloids arose at the molar ratios H2Se(H2S)/HAuCl4 less than 2. At higher ratios, pre-nucleation “dense liquid” species having the hydrodynamic diameter of 20–40 nm, zeta potential −40 mV to −50 mV, and the indirect band gap less than 1 eV derived from the UV-vis spectra grow into submicrometer droplets over several hours, followed by fractional nucleation in the interior and coagulation of disordered gold chalcogenide. XPS found only one Au+ site (Au 4f7/2 at 85.4 eV) in deposited AuSe, surface layers of which partially decomposed yielding Au0 nanoparticles capped with elemental selenium. The liquid species became less dense, the gap approached 2 eV, and gold chalcogenide destabilized towards the decomposition with increasing H2S content. Therefore, the reactions proceed via the non-classical mechanism involving “dense droplets” of supersaturated solution and produce AuSe1−xSx/Au nanocomposites.

Ti-Co mixed oxide as photocatalysts in the generation of hydrogen from water

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Alejandro Pérez-Larios ◽  
Isabel Torres-Ramos ◽  
Rodolfo Zanella ◽  
José Luis Rico
Keyword(s):  
Electron Microscope ◽  
Photoelectron Spectroscopy ◽  
Mixed Oxides ◽  
Uv Light ◽  
Energy Dispersive Spectrometer ◽  
Sol Gel ◽  
X Ray ◽  
Surface Areas ◽  
Vis Spectroscopy ◽  
Xrd Patterns

Abstract The effect of Co into the titanium oxide matrix as photocatalysts in the generation of hydrogen from water is herein reported. Ti–Co mixed oxides and pure titania were synthetized by sol-gel. The Co content was 0, 1, 3, 5, and 10 wt.%. The solids were characterized by Scanning electron microscope-energy dispersive spectrometer (SEM-EDS), N2 physisorption, X-ray difrraction (XRD), ultraviolet visible spectroscopy (UV–Vis), spectroscopy Raman, X-ray photoelectron spectroscopy (XPS) spectroscopy and High resolution transmission electron microscope (HRTEM). The results showed that the mixed oxides show larger specific surface areas (73–186 m2/g) compare to that of pure TiO2 (64 m2/g). The XRD patterns of the Ti-Co samples resemble that of anatase and segregation of Co was not observed by this technique. The band gap energies of these solids vary from 3.05 to 2.85 eV which are smaller than that of pure TiO2 (3.2 eV). The Ti-Co oxides showed an enhancement in the hydrogen production (∼3056 μmol/h) compare to that of TiO2 (190 μmol/h) when using UV light. Furthermore, the photocatalytic activity of titania (110 μmol/h) for this reaction was also smaller than those observed for the Ti-Co mixed oxides (∼4056 μmol/h) under visible light.

Preparation and Photocatalytic Activity of N-TiO2/Sepiolite Nanocomposite

2011 ◽  
Vol 694 ◽  
pp. 85-90
Author(s):  
Dai Mei Chen ◽  
Hai Peng Ji ◽  
Jian Xin Wang ◽  
Jian Chen ◽  
Zheng Ming Wu ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Methylene Blue Degradation ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Photocatalytic Reactions ◽  
Nitrogen Contents

To utilize visible light and separate of TiO2 nanoparticles more efficiently in photocatalytic reactions, nitrogen doped TiO2/sepiolite composites (N-TiO2/sep) with different nitrogen contents were prepared by a sol-gel method and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. XRD showed that anatase-TiO2 nanoparticles were loaded on the surface of sepiolite. XPS revealed that N atoms could incorporate into the lattice of anatase TiO2 substituting the sites of oxygen atoms. UV-vis spectroscopy showed that the visible light absorption of N-TiO2/sep samples decreased with the increase of calciantion temperature and increased with the increase of N content. The photocatalytic activities of obtained N-TiO2/sep samples were evaluated by methylene blue degradation under visible light irradiation. It was found that the N-TiO2/sep samples had the higher photocatalytic activity than that of TiO2/sep.

scholarly journals Catalytic performance of the Ce-doped LaCoO3 perovskite nanoparticles

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Anees A. Ansari ◽  
Syed F. Adil ◽  
Manawwer Alam ◽  
N. Ahmad ◽  
Mohamed E. Assal ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Oxygen Vacancies ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Catalytic Performance ◽  
Temperature Program Reduction ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Optimum Reaction ◽  
Perovskite Nanoparticles

Abstract A series of La1-xCexCoO3 perovskite nanoparticles with rhombohedral phases was synthesized via sol–gel chemical process. X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Electron Diffraction Spectroscopy (EDS), Thermogravimetric Analysis (TGA), UV–Vis spectroscopy, Fourier Transform Infrared spectra (FTIR), Nitrogen Adsorption/desorption Isotherm, Temperature Program Reduction/Oxidation (TPR/TPO), X-ray Photoelectron Spectroscopy (XPS) techniques were utilized to examine the phase purity and chemical composition of the materials. An appropriate doping quantity of Ce ion in the LaCoO3 matrix have reduced the bond angle, thus distorting the geometrical structure and creating oxygen vacancies, which thus provides fast electron transportation. The reducibility character and surface adsorbed oxygen vacancies of the perovskites were further improved, as revealed by H2-TPR, O2-TPD and XPS studies. Furthermore, the oxidation of benzyl alcohol was investigated using the prepared perovskites to examine the effect of ceria doping on the catalytic performance of the material. The reaction was carried out with ultra-pure molecular oxygen as oxidant at atmospheric pressure in liquid medium and the kinetics of the reaction was investigated, with a focus on the conversion and selectivity towards benzaldehyde. Under optimum reaction conditions, the 5% Ce doped LaCoO3 catalyst exhibited enhanced catalytic activity (i.e., > 35%) and selectivity of > 99%, as compared to the other prepared catalysts. Remarkably, the activity of catalyst has been found to be stable after four recycles.

The adsorption and dispersing mechanisms of sodium lignosulfonate on Al2O3 particles in aqueous solution

Holzforschung ◽  
2013 ◽  
Vol 67 (4) ◽  
pp. 387-394 ◽  
Author(s):  
Rong Li ◽  
Dongjie Yang ◽  
Wenyuan Guo ◽  
Xueqing Qiu
Keyword(s):  
Metal Cation ◽  
Photoelectron Spectroscopy ◽  
Low Ph ◽  
Repulsive Force ◽  
Sodium Lignosulfonate ◽  
Aggregation State ◽  
Potential Measurement ◽  
X Ray ◽  
Ph Values ◽  
Vis Spectroscopy

Abstract The adsorption behavior and dispersion efficiency of sodium lignosulfonate (NaLS) on Al2O3 particles at different pH values were investigated by UV-Vis spectroscopy, zeta potential measurement, X-ray photoelectron spectroscopy, and viscosity measurements. The effects of the additives urea, Na2SO4, and NaCl were tested. At low pH values, NaLS adsorbed on the Al2O3 particles in the form of aggregates and at high pH values as separated single molecules. At pH 3–11, the adsorption was not affected through addition of urea, ruling out hydrogen bond as a controlling factor. By adding Na2SO4 and NaCl, the main driving force was the synergistic effect of the electrostatic interaction and the metal cation-π interaction at pH<pHIEP (IEP, isoelectric point), whereas the metal cation-π interaction was dominant at pH>pHIEP. The dispersing mechanism was mainly attributed to the steric hindrance (at pH<pHIEP) and the electrostatic repulsive force (at pH>pHIEP) owing to the differences in the aggregation state of the adsorbed molecules.

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