scholarly journals One-Step Preparation of RGO/Fe3O4-Fevo4 Nanocomposites As Highly Effective Photocatalysts Under Natural Sunlight Illumination

2022 ◽  
Author(s):  
Qana A. Alsulami ◽  
A. Rajeh ◽  
Mohammed A. Mannaa ◽  
Soha M. Albukhari ◽  
Doaa F. Baamer
Keyword(s):  
Crystal Structure ◽  
Methylene Blue ◽  
Brilliant Green ◽  
Visible Region ◽  
Band Gap Energy ◽  
Photocatalytic Reaction ◽  
Gap Energy ◽  
Photodegradation Efficiency ◽  
One Step ◽  
Kinetics Of

Abstract The study used a one-step hydrothermal method to prepare Fe3O4-FeVO4 and xRGO/Fe3O4-FeVO4 nanocomposites. XRD, TEM, EDS, XPS, DRS, and PL techniques were used to examine the structurally and morphologically properties of the prepared samples. The XRD results appeared that the Fe3O4-FeVO4 has a triclinic crystal structure. Under hydrothermal treatment, (GO) was effectively reduced to (RGO) as illustrated by XRD and XPS results. UV-Vis analysis revealed that the addition of RGO enhanced the absorption in the visible region and narrowed the band gap energy. The photoactivities of the prepared samples were evaluated by degrading methylene blue (MB), phenol and brilliant green (BG) under sunlight illumination. As indicated by all the nanocomposites, photocatalytic activity was higher than the pure Fe3O4-FeVO4 photocatalyst, and the highest photodegradation efficiency of MB and phenol was shown by the 10%RGO/Fe3O4-FeVO4. In addition, the study examined the mineralization (TOC), photodegradation process, and photocatalytic reaction kinetics of MB and phenol.

Effects of L-Cysteine on the Photoluminescence Properties of ZnO:S Quantum Dots

2020 ◽  
Vol 842 ◽  
pp. 242-250
Author(s):  
Wen Dai ◽  
Shu Wang Duo ◽  
Xiao Xia Li ◽  
Zhong Chen ◽  
Zi Chuan Zheng ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Quantum Dots ◽  
Band Gap ◽  
Visible Region ◽  
Average Crystallite Size ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Microwave Hydrothermal ◽  
Uv Emission ◽  
Zno Crystal

ZnO:S quantum dots (QDs) were synthesized by a microwave hydrothermal method. The effects of L-cysteine (L-cys) on the crystal structure, size, morphology, band gap energy and photoluminescence (PL) properties were studied by XRD, EDS, TEM, FTIR, DRS and PL spectroscopy, respectively. The XRD results showed that all samples had a wurtzite structure ZnO crystal structure and the average crystallite size was 8.4, 5.8, and 9.2 nm for ZnO, ZnO:S and L-cys capped ZnO:S (LZOS) QDs, respectively. The EDS, HRTEM and FTIR results confirmed L-cys was capped on the surface of ZnO:S QDs. It was found that the band gap energy was 3.25, 3.29 and 3.31 eV for ZnO, ZnO:S and LZOS QDs, successively. PL spectrum of ZnO QDs showed two emission peaks in the UV and visible region, respectively. When doping S into ZnO, the intensity of the UV emission reduced, while the intensity of the visible emission dramatically increased. Also, L-cys coated obviously enhanced the PL intensity of ZnO:S QDs. This work suggested that LZOS QDs could be applied in luminescent devices.

Photoelectrochemical Properties of Alkali-treated Sodium Titanate Nanorods

2015 ◽  
Vol 1784 ◽  
Author(s):  
Mingu Kim ◽  
Gwanghyo Choi ◽  
Daeheung Yoo ◽  
Kwangmin Lee
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Band Gap ◽  
Heat Treatment Temperature ◽  
Alkali Treatment ◽  
Sodium Titanate ◽  
Band Gap Energy ◽  
Treatment Temperature ◽  
Photoelectrochemical Properties ◽  
Gap Energy

ABSTRACTThe band gap energy of the TiO2 photocatalytic is high at 3.2 eV. Ultraviolet (UV) light irradiation (<388nm) is required for the photocatalytic application. The lowering the band gap energy of TiO2 and enlarging light absorbing area are effective ways to enhance the efficiency of photocatalytic activity. Furthermore, the morphology and crystal structure of nanosized TiO2 considerably influences its photocatalytic behavior.In this study, sodium titanate nanorods were formed using an alkali-treatment and were heat treated at different temperatures. The photoelectrochemical properties of sodium titanate nanorods was measured as a function of heat treatment temperature. The nanorods were prepared on the surface of Ti disk with a diameter of 15mm and a thickness of 3mm. Ti disk was immersed in 5 M NaOH aqueous solution at a temperature of 60 °C for 24 h. Morphology of sodium titanate nanorods was observed using FE-SEM. Crystal structure of sodium titanate nanorods was analyzed using X-ray diffractometer. Photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) was used to evaluate photoelectrochemical properties of sodium titanate nanorods. The thin amorphous sodium titanate layer was formed during alkali-treatment. The sodium titanate layer was changed to nanorods after heat treatment at a temperature of 700 °C. The thickness and length of sodium titanate nanorods obtained at 700 °C were around 100 nm and 1μm, respectively. The crystal structure of sodium titanate was identified with Na2Ti6O13. Above 900 °C, the morphology of nanorods changed to agglomerated shape and the thickness of nanorods increased to 1 μm. The lowest value of PL was obtained at a temperature of 700 °C, while nonalkali treated specimen showed the highest value of PL. EIS revealed that polarization resistance at interface between sodium titanate nanorods and electrolyte was increased with increasing heat treatment temperature.

scholarly journals Effect of thickness on the optical properties of Gaas thin films

2013 ◽  
Vol 37 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Chitra Das ◽  
Jahanara Begum ◽  
Tahmina Begum ◽  
Shamima Choudhury
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Band Gap ◽  
Optical Band Gap ◽  
Visible Region ◽  
Solar Spectrum ◽  
Band Gap Energy ◽  
Optical Parameters ◽  
Gap Energy

Effect of thickness on the optical and electrical properties of gallium arsenide (GaAs) thin films were studied. The films of different thicknesses were prepared by vacuum evaporation method (~10-4 Pa) on glass substrates at a substrate temperature of 323 K. The film thickness was measured in situ by a frequency shift of quartz crystal. The thicknesses were 250, 300 and 500 nm. Absorption spectrum of this thin film had been recorded using UV-VIS-NIR spectrophotometer in the photon wavelength range of 300 - 2500 nm. The values of some important optical parameters of the studied films (absorption coefficient, optical band gap energy and refractive index; extinction co-efficient and real and imaginary parts of dielectric constant) were determined using these spectra. Transmittance peak was observed in the visible region of the solar spectrum. Here transmittance showed better result when thicknesses were being increased. The optical band gap energy was decreased by the increase of thickness. The refractive index increased by increasing thickness while extinction co-efficient and real and imaginary part of dielectric constant decreased. DOI: http://dx.doi.org/10.3329/jbas.v37i1.15684 Journal of Bangladesh Academy of Sciences, Vol. 37, No. 1, 83-91, 2013

Synthesis,Surface Morphology, Optical Properties and Photocatalyst Activities of TiO2/ZnO/Fe2O3 Nanocomposites.

2020 ◽  
Author(s):  
Juliya Acha Parambil ◽  
Abdul Mujeeb V.M ◽  
S. Zh. Karazhanov ◽  
Jayaram Peediyekkal
Keyword(s):  
Methylene Blue ◽  
Optical Properties ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Photoluminescence Intensity ◽  
Methylene Blue Degradation ◽  
Gap Energy ◽  
First Order ◽  
First Order Kinetics ◽  
Transition Surface

Abstract The photocatalytic degradation of methylene blue in aqueous solutions is enhanced significantly by formulating multiphase TiO2/ZnO/Fe2O3 nanocomposites. The photocatalytic activity of unary TiO2, binary TiO2/ZnO, and ternary TiO2/ZnO/Fe2O3 compounds are compared and reported. Using TiO2/ZnO/Fe2O3, methylene blue degradation became rapid and the reaction followed first-order kinetics. The consequences of the phase transition, surface features, and optical properties are compared and elucidated. The reduced photoluminescence intensity and decreased optical band gap energy in tertiary compounds impose higher degradation of methylene blue under irradiation.

Effect of Nb doping on morphology, crystal structure, optical band gap energy of TiO2 thin films

2014 ◽  
Vol 14 (3) ◽  
pp. 421-427 ◽  
Author(s):  
Deuk Yong Lee ◽  
Ju-Hyun Park ◽  
Young-Hun Kim ◽  
Myung-Hyun Lee ◽  
Nam-Ihn Cho
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Tio2 Thin Films ◽  
Gap Energy ◽  
Nb Doping

scholarly journals Silica Supported Copper-Nickel Oxide Catalyst for Photodegradation of Methylene Blue

2019 ◽  
Vol 31 (12) ◽  
pp. 2891-2896
Author(s):  
A.K. Prodjosantoso ◽  
S. Kamilia ◽  
M.P. Utomo ◽  
K.S. Budiasih
Keyword(s):  
Methylene Blue ◽  
Oxide Catalyst ◽  
Catalyst Activity ◽  
Band Gap Energy ◽  
Organic Wastes ◽  
Visible Spectroscopy ◽  
Gap Energy ◽  
Langmuir Adsorption ◽  
Activity Test ◽  
Uv Visible

Organic wastes are often harmful for organisms living in water. The compounds may toxic and or carcinogenic. Many methods have been applied to minimize the organic wastes in water, one of which is through fotodegradation process using catalysts. This report is about the use of (Cu-Ni)Ox@SiO2 catalyst for photodegration the methylene blue under the sunlight exposure. A serial method of XRD, SEM-EDX and UV-visible spectroscopy has been used in the study. The catalyst adsorption test was carried out in the dark environment, whilst the catalyst activity test in photodegradation of methylene blue was performed under the sunlight. The measurements on (Cu-Ni)Ox@SiO2 catalyst clearly indicate the presence of tridymite silica (SiO2) with the particle size around 9 nm. The silica band gap energy decreases with the adsorption of copper and nickel on the surface of silica. The adsorption follows the Langmuir adsorption isotherm. The (Cu-Ni)Ox@SiO2 is significantly catalyzed the degradation of methylene blue in water.

Increasing Rutile Phase Amount in Chromium-Doped Titania by Simple Stirring Approach for Photodegradation of Methylene Blue under Visible Light

2015 ◽  
Vol 68 (7) ◽  
pp. 1129 ◽  
Author(s):  
Pei Wen Koh ◽  
Leny Yuliati ◽  
Hendrik O. Lintang ◽  
Siew Ling Lee
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Band Gap ◽  
Rutile Phase ◽  
Band Gap Energy ◽  
Synthesis Process ◽  
Doped Tio2 ◽  
Gap Energy ◽  
Stirring Time ◽  
Doped Titania

The amount of rutile phase in chromium-doped titania photocatalyst was controlled by varying stirring time (0.5–2.0 h) at room temperature during a sol–gel synthesis process. The percentage of rutile phase increased from 15.1 % to 28.6 % when stirring time was prolonged from 0.5 to 1.5 h. Further increases in the stirring time had negligible effect on the rutile phase amount. As evidenced by analyses using diffuse reflectance ultraviolet–visible spectroscopy and X-ray photoelectron spectroscopy, a sufficient stirring time was important for more substitution of Cr3+ for Ti4+ in the lattice, resulting in anatase-to-rutile phase transformation. The formation of more rutile phase in Cr-doped TiO2 not only reduced the band gap energy, but also induced surface defects that retarded electron–hole recombination. It has been demonstrated that the Cr-doped TiO2 prepared with a stirring time of 1.5 h possessed the lowest band gap energy of 1.89 eV, and hence it achieved the highest photodegradation of methylene blue under visible light irradiation.

scholarly journals The effect of doping variation on band gap energy and crystal structure of Biochar/TiO2 thin layer

2021 ◽  
Vol 1731 ◽  
pp. 012060
Author(s):  
H D Fahyuan ◽  
F Deswardani ◽  
N Nurhidayah ◽  
M F Afrianto ◽  
H Heriansyah ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thin Layer ◽  
Band Gap ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Effect Of Doping

Effect of 2,4-dinitrophenol dye doping on tristhioureazinc(II) sulfate single crystals: a potential nonlinear optical material

2020 ◽  
Vol 53 (4) ◽  
pp. 972-981 ◽  
Author(s):  
G. Durgababu ◽  
G. J. Nagaraju ◽  
G. Bhagavannarayana
Keyword(s):  
Crystal Structure ◽  
Band Gap ◽  
Single Crystals ◽  
Nonlinear Optical ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Optical Range ◽  
Gap Energy ◽  
Uv Visible ◽  
Crystalline Matrix

Good quality single crystals of 2,4-dinitrophenol (DNP)-doped tristhioureazinc(II) sulfate (ZTS) were successfully grown by employing the simple and cost effective slow-evaporation solution technique. To study the effect of doping on various device properties, the grown single crystals were subjected to powder X-ray diffraction (PXRD), high-resolution XRD, thermogravimetric analysis (TGA), Vickers hardness testing, and UV–visible, photoluminescence (PL) and Fourier transform IR (FTIR) spectroscopy techniques. The crystal structure of DNP-doped ZTS bulk single crystals remained the same as the crystal structure of ZTS. However, the changes in intensities of the diffraction peaks in the PXRD spectra indicated the incorporation of dopants into the crystalline matrix. FTIR studies confirm the incorporation of dopants into the crystalline matrix, shown by the shifting of certain prominent absorption bands towards higher energy. This also indicated the induced useful strain due to doping, leading to charge transfer and the enhancement of nonlinear optical properties. The cut-off wavelength and optical band gap energy of pure ZTS and DNP-doped ZTS crystals were studied by UV–visible absorption spectroscopy, revealing a slight reduction in the optical band gap energy due to doping, which in turn revealed the enhancement of the optical range. PL studies revealed an enhanced optical range of photoluminescence in ZTS crystals. Second harmonic generation (SGH) studies carried out by the Kurtz powder technique revealed the enhancement of SHG value due to DNP doping. To ensure the thermal stability and mechanical strength of the grown crystals with doping (required from the point of view of device applications), TGA and Vicker's hardness studies were performed.

scholarly journals Dielectric, optical and enhanced photocatalytic properties of CuCrO2 nanoparticles

RSC Advances ◽  
2017 ◽  
Vol 7 (44) ◽  
pp. 27549-27557 ◽  
Author(s):  
Tokeer Ahmad ◽  
Ruby Phul ◽  
Parvez Alam ◽  
Irfan H. Lone ◽  
Mohd. Shahazad ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Band Gap ◽  
Surface Area ◽  
Band Gap Energy ◽  
Catalytic Degradation ◽  
Photocatalytic Properties ◽  
Sunlight Irradiation ◽  
Gap Energy ◽  
Precursor Route ◽  
Citrate Precursor

Delafossite CuCrO2 nanoparticles with band gap energy of 3.09 eV and surface area of 235 m2 g−1 were prepared by citrate precursor route showed enhanced catalytic degradation of methylene blue in H2O under the sunlight irradiation.

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