scholarly journals Synergistic Improvement in Coating with UV Aging Resistance and Anti-Corrosion via La-Doped CeO2 Powders

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1095
Author(s):  
Ang Tian ◽  
Tengda Ma ◽  
Xiaoguo Shi ◽  
Dixiang Wang ◽  
Wenyuan Wu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
Ultraviolet Rays ◽  
Doped Ceria ◽  
Oxalate Precipitation ◽  
Roasting Process ◽  
Aging Properties ◽  
Ultraviolet Light Irradiation ◽  
La Doped

Benefitting from a suitable band gap, ceria is an excellent material for UV shielding. By solid solution doping and specific micromorphology, its band gap can be effectively controlled. In this paper, ceria doped with lanthanum via oxalate precipitation is combined with a high-temperature roasting process. The properties of the prepared samples are characterized by UV–Vis diffuse reflectance spectroscopy (DRS), Raman, XRD, FESEM and XPS. The absorption threshold of materials is clearly red-shifted in the ultraviolet band, which originates from the electron-phonon generation. To further reveal the mechanism, the density function theory calculation (DFT) is implemented to study the influence of lanthanum concentrations on ceria’s band gap. It is demonstrated that the band gap can even be narrowed to 2.97 eV by optimizing the sintering temperature and lanthanum-doped concentration. To investigate its improved anti-aging properties under ultraviolet rays, different amounts of 5% lanthanum-doped ceria is mixed with an Al-based coating and then coated on the Q235 steel. Combined with an ultraviolet light irradiation experiment and electrochemical test technology, the corrosion resistance of the modified coatings is evaluated. The coating with 20% La-doped ceria provides the best corrosion resistance performance.

Enhanced visible-active photocatalytic behaviors observed in Mn-doped BiFeO3

2018 ◽  
Vol 32 (17) ◽  
pp. 1850185 ◽  
Author(s):  
Yun-Hui Si ◽  
Yu Xia ◽  
Ya-Yun Li ◽  
Shao-Ke Shang ◽  
Xin-Bo Xiong ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Mn Doped ◽  
Hole Recombination ◽  
Narrow Band Gap Semiconductors

A series of BiFeO3 and BiFe[Formula: see text]Mn[Formula: see text]O3 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by a hydrothermal method. The samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy (EDS) and UV–Vis diffuse reflectance spectroscopy, and their photocatalytic activity was studied by photocatalytic degradation of methylene blue in aqueous solution under visible light irradiation. The band gap of BiFeO3 was significantly decreased from 2.26 eV to 1.90 eV with the doping of Mn. Furthermore, the 6% Mn-doped BiFeO3 photocatalyst exhibited the best activity with a degradation rate of 94% after irradiation for 100 min. The enhanced photocatalytic activity with Mn doping could be attributed to the enhanced optical absorption, increment of surface reactive sites and reduction of electron–hole recombination. Our results may be conducive to design more efficient photocatalysts responsive to visible light among narrow band gap semiconductors.

Kr and Xe irradiations in lanthanum (La) doped ceria: Study at the high dose regime

2011 ◽  
Vol 418 (1-3) ◽  
pp. 80-86 ◽  
Author(s):  
Di Yun ◽  
Aaron J. Oaks ◽  
Wei-ying Chen ◽  
Marquis A. Kirk ◽  
Jeffrey Rest ◽  
...  
Keyword(s):  
High Dose ◽  
Doped Ceria ◽  
Dose Regime ◽  
La Doped

scholarly journals Blue to Yellow Photoluminescence Emission and Photocatalytic Activity of Nitrogen Doping in TiO2Powders

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Gabriela Byzynski ◽  
Caue Ribeiro ◽  
Elson Longo
Keyword(s):  
Photocatalytic Activity ◽  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
Anatase Phase ◽  
Oh Radical ◽  
Additional Energy ◽  
Photoluminescence Emission ◽  
Radical Production ◽  
N Doping ◽  
Band Gap Structure

The defects caused by doping are important for understanding the increased photocatalytic activities of TiO2:N in organic reactions and in the evaluation of OH radical production after doping. TiO2:N was therefore synthesized using a modified polymeric method and N doping was performed by calcination with urea. The resulting powders were characterized using field emission scanning electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, Raman spectroscopy, Fourier transformation infrared spectroscopy, and photoluminescence emission spectroscopy (PL). N doping did not alter the morphology of the nanoparticles, and the anatase phase predominated, with the retention of the rutile phase. The band gap values, superficial areas, and crystallite sizes of the powders decreased after doping. The PL results showed an additional energy level in the TiO2:N band gap structure as a result of TiO2lattice defects caused by doping. At low N contents, the powders showed continuous emissions from the blue region to the yellow region and a high N content shifted the PL emissions to the red region. These results suggest that the use of these powders could increase the efficiencies of solar cells and water-splitting processes. The photocatalytic activity of the powders under UVC illumination was confirmed for different organic dye molecules. The OH radical production did not change extensively after doping, as shown by experiments with terephthalic acid, and higher photocatalytic efficiencies in Rhodamine-B degradation under UVC illumination were achieved using the doped samples.

Study on Band Gap Energy of F Doped TiO2 Nanotubes

2017 ◽  
Vol 889 ◽  
pp. 234-238
Author(s):  
Mohd Hasmizam Razali ◽  
Nur Arifah Ismail ◽  
Mahani Yusoff
Keyword(s):  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
Small Diameter ◽  
Ultra Violet ◽  
Band Gap Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gap Energy ◽  
Transmission Electron ◽  
Xrd Patterns

Pure and F doped TiO2 nanotubes was synthesized using simple hydrothermal method. The hydrothermal was conducted using teflon-liner autoclave and maintained at 150oC for 24 hours. The characterization of synthesised product was carried out using x-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive of x-ray spectroscopy (EDX) and ultra violet – visible light diffuse reflectance spectroscopy (UV-Vis DRS) for band gap measurements. XRD patterns indicated that anatase TiO2 phase was remained after F doping suggested that fluorine was highly dispersed into TiO2 by substituted with O in the TiO2 lattice to formed TiO2-xFx solid solution. Morphology investigation using TEM found out small diameter of nanotubes structure within 8 – 10 nm of pure and F doped TiO2 nanotubes. The band gap energy (Eg) of both nanotubes samples were almost similar proposing that F doping does not modify the band gap energy.

A Microwave Route for the Synthesis of Nanoflakes and Dendrites-Type β-In2S3 and their Characterization

2006 ◽  
Vol 6 (3) ◽  
pp. 845-851 ◽  
Author(s):  
Chitta Ranjan Patra ◽  
Sujata Patra ◽  
Alexandra Gabashvili ◽  
Yitzhak Mastai ◽  
Yuri Koltypin ◽  
...  
Keyword(s):  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
High Yield ◽  
Nano Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Photo Acoustic Spectroscopy

In this article, a simple microwave route was applied for the synthesis of nanoflakes and dendrite-type β-indium sulfide (In2S3) in high yield (>97%), using a homogeneous mixture of indium(III)chloride and thiourea in an ethylene glycol (EG)/polyethylene glycol (PEG400) solvent. The reaction was conducted in a simple domestic microwave oven (DMO). Powder X-ray diffraction (XRD), low resolution and high resolution transmission electron microscopy (LRTEM and HRTEM), selected area electron diffraction (SAED), and energy dispersive X-ray spectroscopy (EDS), were applied to investigate the crystallinity, structure, morphology, and composition of the In2S3 nano-materials. Both the as-synthesized and calcined In2S3 products were a body-centered tetragonal (bct) phase, observed by XRD and HRTEM. The length and width of the resulting nanoflakes were in the range of 70–600 nm and 4–10 nm, respectively. The optical band gap of the powder was determined by diffuse reflectance spectroscopy (DRS) and was found to be 2.44 eV. The electronic properties of the products were studied by measuring the optical absorption spectra using photo-acoustic spectroscopy. The band gap calculated by this method was found to be 2.52 eV. A possible mechanism for the formation of nanoflakes/dendrites-type In2S3 was also discussed.

Optical Properties of PZT, PLZT, and PNZT Thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
Chien H. Peng ◽  
Jhing-Fang Chang ◽  
Seshu B. Desu
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Pzt Films ◽  
Direct Band ◽  
Band Transition ◽  
La Doped

AbstractOptical properties were investigated for undoped, La-doped, and Nd-doped Pb(ZrxTi1-x)O3 thin films deposited on sapphire substrates by metalorganic decomposition (MOD) process. Refractive index and extinction coefficient of these films were calculated from transmission spectra in the wavelength range of 300 to 2000 nm. The packing densities of these films were calculated from the refractive index data by using the effective medium approximation. Band gap energies of these films were also reported under the assumption of direct band-to-band transition. The refractive index and band gap energy of PZT films showed a linear dependence on Zr/Ti ratio. The refractive index decreased, while the band gap energy increased with increasing zirconium content. It was also found that both La-doped and Nd-doped PZT films had higher refractive indices than those of undoped PZT films with the same Zr/Ti ratio (50/50).

scholarly journals Synthesis and Characterization Titanium Dioxide (TiO2) Doped Vanadium(V) Using Solid State Method

ALCHEMY ◽  
2015 ◽  
Vol 4 (1) ◽  
Author(s):  
Khusnan Mustofa ◽  
Nur Aini ◽  
Susi Nurul Khalifah
Keyword(s):  
Titanium Dioxide ◽  
Solid State ◽  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
Synthesis Method ◽  
Band Gap Energy ◽  
Solid State Method ◽  
Gap Energy ◽  
Wavelength Absorption ◽  
State Method

<p>TiO<sub>2</sub> Anatase activities should be increased from the UV to the visible light photocatalytic activity of TiO<sub>2</sub> to increase anatas. One efforts to optimize TiO<sub>2</sub> anatase activity is doping by using dopant vanadium(V). Synthesis method which is used in this research is a solid reaction method. The steps being taken in this methods include grinding and heating at high temperatures. Dopant concentrations of vanadium(V) which are used in the research was 0.3%, 0.5% and 0.7%. and the characterization used is X-ray diffraction and UV-Vis Diffuse Reflectance Spectroscopy. The result shows that there are a changing of particle size, band gap energy, and absorption of TiO<sub>2</sub> anatas wavelength because of dopan vanadium(V) addition. While TiO<sub>2</sub>’s structure does not change. The crystal sizes of each TiO<sub>2</sub> without doping, V-TiO<sub>2</sub> 0,3%, 0,5% and 0,7% are 53.21 nm, 47.67 nm, 79.65 nm dan 68.99 nm.  Band gap energy of each TiO<sub>2</sub> without doping, V-TiO<sub>2</sub> 0,3%, 0,5% dan 0,7% are 3.309 eV, 3.279 eV, 3.270 eV and 3.259 eV. While wavelength absorption of each TiO<sub>2</sub> without doping, V-TiO<sub>2</sub> 0,3%, 0,5% and 0,7% are 374.9 nm, 378.4 nm, 379.5 nm and 380.8 nm.<em> </em></p><p class="BodyAbstract"> </p><strong><em>Keywords</em>:</strong> <em>Synthesis, titanium dioxide, vanadium(V), solid state method</em>

Characterization and Photocatalytic Activity of Microspheres ZnO by Hydrothermal Method

2019 ◽  
Vol 814 ◽  
pp. 487-492
Author(s):  
Xi Hao Lin ◽  
Pei Song Tang ◽  
Bei Bei Wang ◽  
Hai Qiang Tang
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Hydrothermal Method ◽  
Diffuse Reflectance Spectroscopy ◽  
Raw Materials ◽  
Average Diameter ◽  
High Photocatalytic Activity ◽  
X Ray Diffraction ◽  
Excellent Photocatalytic Activity ◽  
Ultraviolet Light Irradiation

Using zinc acetate, glycerol alcohol and sodium hydroxide as principal raw materials, the ZnO microspheres were prepared by hydrothermal method at 200°C. The samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectroscopy (DRS). Using methyl orange as the degradation object, the photocatalytic activities and recycling stability of ZnO were characterized. The results show that ZnO samples are spherical and the average diameter is approximately 3-4μm. Moreover, the bandgap width is 3.1eV. Under ultraviolet light irradiation, it is testified that ZnO shows a excellent photocatalytic activity for the degradation of methyl orange. From experience, we can draw a conclusion that the ZnO samples were in line with first-order kinetics, with an apparent rate constant of 0.016min-1. At the same time, ZnO showed excellent recycling performance. Although the samples have been recycled three times, it still maintained high photocatalytic activity.

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