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Photocatalytic performance of K2Ti6O13 whiskers to H2 evolution and CO2 photo-reduction
摘要： K 2 Ti 6 O 13 whiskers were synthesized by conventional sol-gel method, sono-chemical assisted and microwave assisted sol-gel method in order to obtain catalysts with different particle sizes and to modify their optical, textural and electrochemical properties. These modifications improved their photocatalytic activity for H 2 evolution and CO 2 photo-reduction. Long K 2 Ti 6 O 13 whiskers prepared by ultrasound assisted sol-gel method are the most active photocatalysts for the hydrogen evolution reaction using pure water as reactant (U-SG, 10,065 μmol g ?1 ). In contrast, an opposite behavior was observed using a mixture of ethanol-water, where the highest activity was achieved by the shortest and less crystalline K 2 Ti 6 O 13 whiskers (C-SG, h32871 μmol g ?1 ). In case of CO 2 photo-reduction, long whiskers that were also prepared by the sono-chemical assisted sol-gel method were the most active to transform CO 2 to formaldehyde, methane, methanol and hydrogen. The E FB value of this catalyst is located very close to the potential for formaldehyde production and favors the selectivity to this organic product.
关键词： Sol-gel,Whiskers,Hydrogen evolution,K 2 Ti 6 O 13,CO 2 reduction
更新于2025-09-10 09:29:36
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Effect of titanium (IV) isopropoxide molarity on the crystallinity and photocatalytic activity of titanium dioxide thin film deposited via green sol–gel route
摘要： In this paper, the effect of titanium (IV) isopropoxide TTIP molarity on the crystallinity and TiO2 thin film properties deposited via green sol–gel route was reported. The green sol–gel route is a pioneering approach for eco-friendly coating where solvent is not utilized in the sol formulation. This is in contrast to the common TiO2 sol formulation where solvent is used despite the long term harmful the environment. TiO2 solution with different TTIP molarity of 0.2 M, 0.3 M, 0.4 M and 0.5 M were utilized during coating deposition. Deposition were conducted for ten times using dip coating and treated at 500 ?C (1-h). The crystalline phases and phase content were characterized using X-ray diffraction (XRD) and reference intensity ratio (RIR) equation. Crystallites size was obtained by Scherrer’s equation while coating morphologies was analyzed using scanning electron microscope (SEM). The photocatalytic activity was conducted by the degradation of methylene blue (MB) towards UV-light and visible light. At higher TTIP molarity (0.5 M), higher crystallinity of mixed anatase (～17 nm) and rutile (～29 nm) phases were obtained along with homogeneous coating (cracking and visible pore). Also, higher MB degradation were obtained at UV-light (95%) and visible-light (86%) irradiation. In conclusion, higher TTIP molarity produced TiO2 film with higher crystallinity, small crystallite size, cracking morphology thus contribute good performance in photocatalytic activity. Findings in this work shown that TiO2 thin film deposition is possible conducted without the use of solvent through optimized formulation of only precursor, acid and water. This is beneficial for the environment sustainability.
关键词： Sol–gel dipping,Titanium dioxide,Green route,Solvent free,Titanium (IV) isopropoxide,Photocatalytic activity
更新于2025-09-10 09:29:36
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Structure characterization and photoluminescence of sol-gel synthesized Ag-Dy-codoped silica phosphor
摘要： Bulk samples of single Ag-, Dy-doped and Ag-Dy-codoped silica matrices were synthesized using the sol-gel processing. These matrices were characterized using X-ray di?ractometry, ultraviolet-visible-near infrared (UV-VIS-NIR), Fourier transform infrared, photoluminescence (PL) excitation and emission spectroscopic techniques. High resolution transmission electron microscope con?rmed the presence of ?ne spherical Ag nanoparticles (NPs), whose average size is approximately 10–15 nm, in the Ag-doped and Ag-Dy-codoped silica matrices. UV-VIS-NIR spectra revealed absorption peaks due to Dy3+ active centers in addition to the surface plasmon resonance bands of Ag NPs centered at 410 and 452 nm in these matrices, respectively. UV-excited PL of the materials was studied and compared. Near-white light emission, which was assessed by the calculated CIE chromaticity coordinates, could be observed under UV excitation at 365 nm in the Ag-Dy-codoped silica matrix. This white light was realized by appropriate combination of prominent yellow and blue emissions. Electron spin resonance spectra revealed paramagnetic spin states for Ag which can be attributed to the quantum size e?ect of very ?ne Ag NPs dispersed in the silica network. The obtained results indicate that the Ag-Dy-codoped silica phosphor could be a promising candidate for application as white light emitting phosphor for UV LED chips.
关键词： Sol-gel,TEM,Surface plasmon resonance,Phosphors,White LED,Optical band gap
更新于2025-09-10 09:29:36
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Structural, optical and magnetic properties of YIG and TbErIG nanofilms prepared using a sol-gel method
摘要： A series of yttrium iron garnet (YIG) and terbium erbium iron garnet (TbErIG) nanocrystalline films were successfully grown using a sol-gel method. A crystalline analysis carried out using an X-ray diffractometer confirmed that all films had a single-phase garnet structure. The TbErIG films annealed in O2 and Ar gas had a larger number of crystallisation peaks, with a lattice constant that was close to the standard value for ErIG. The transparency increased from 94% for YIG (O2) to 98% for TbErIG (O2) films in the near-infrared region. All films were soft ferrite materials, as indicated by their magnetic hysteresis loops. The value of saturated magnetisation was increased for samples annealed in air, and was markedly decreased for samples subjected to O2 and Ar atmospheres. An increase in the coercivity value (91 Oe) was also observed for the TbErIG (Ar) film. YIG and TbErIG showed a phase transition from ferrimagnetic to paramagnetic at the Curie temperature, Tc = 556 K and 557.3 K, respectively. The low saturation magnetisation, low optical absorption and highly crystalline structure of TbErIG (O2 and Ar) films mean that these films may potentially be used in a magneto-optical compact isolator in the visible and NIR regions.
关键词： nanostructures,Sol-gel,magnetic properties,X-ray diffraction,optical properties
更新于2025-09-10 09:29:36
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Structure, photocatalytic and antibacterial activity study of Meso porous Ni and S co-doped TiO2 nano material under visible light irradiation
摘要： Undoped and Ni-S co-doped Mesoporous TiO2 nano materials were synthesized by using sol-gel method. The characteristic features of as prepared catalyst samples were investigated using various advanced spectroscopic and analytical techniques. The characterization results of the samples revelled that all the samples exhibited anatase phase (XRD), decreasing band gap (2.68 eV) (UV-Vis-DRS), small particle size (9.2 nm) (TEM), High surface area (142.156 m2/g) (BET), particles with spherical shape and smooth morphology (SEM), there is a frequency shift observed for co-doped sample (FT-IR) and the elemental composition electronic states and position of the doped elements (Ni and S) in the TiO2 lattice analyzed by XPS and EDX. These results supported the photocatalytic degradation of Bismarck Brown Red (BBR) achieved with in 110 min and also exhibited the antibacterial activity on Staphylococcus aureus (MTCC-3160), Pseudomonas fluorescence (MTCC-1688) under visible light irradiation.
关键词： Sol-gel,photocatalysis under visible light,Antibacterial Activity,Ni-S co-doped TiO2,degradation of Bismarck Brown Red
更新于2025-09-10 09:29:36
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Structural and dielectric properties of BaTi0.5 (Co0.33 Mo0.17) O3 perovskite ceramic
摘要： The polycrystalline sample BaTi0.5 (Co0.33 Mo0.17) O3 was synthesized by the sol-gel method. The effect of replacing titanium by cobalt and molybdenum on the structural and electrical properties of our compound was investigated. The results of X-ray diffraction (XRD) at room temperature showed a pure tetragonal perovskite. The electrical response was studied by complex impedance spectroscopy over a broad frequency range (30 - 106 Hz) at different temperatures. The values of ac conductivity were fitted by Jonscher’s law σ(ω) = σDC + Aωn and supported by the correlated barrier hopping (CBH) mechanism. Complex impedance analysis confirmed the existence of an electrical relaxation in the compound. The dielectric constant and the dielectric loss decreased with the increase in frequency. This behavior can be explained by the presence of the Maxwell–Wagner type of polarization responsible for the electric conduction. The modulus plots were characterized by the Havriliak–Negami (H-N) and the empirical Kohlrausch–Williams–Watts (K.W.W.) functions. The Normalized plot of the imaginary part of modulus indicates that the dynamical processes are temperature independent.
关键词： Impedance spectroscopy,Sol-gel processes,Permittivity,X-ray diffraction,Conductivity
更新于2025-09-10 09:29:36
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Photocatalytic efficiencies of Zn1-xMxO compounds synthesized with a broad panel of M elements: responses in the UV, visible and solar range
摘要： Solar applications in the treatment of waste water fields were limited by the fact that the photocatalytic efficiency of photoreactors, and specifically the photocatalyst used, was less than one percent. Here we report a study investigating the catalysts based on Zn1?xMxO compounds for different [M]/[Zn] atomic ratios. M elements: Na, K, Li, Fe, V, Co, Mg, Mn, Ca, In, Al, P, Ce, were selected. All these catalysts were synthesized by sol-gel process. The morphological, compositional structural and optical properties of the obtained samples were studied by SEM, EDS, XRD and UV-Vis-NIR DRS. To evaluate photocatalytic efficiency, experiments were conducted under controlled irradiation, i.e. ultraviolet, visible or simulated sunlight. The responses showed that when the catalysts were synthesized to capture photons in the visible range, these photons were inefficient at generating radicals. These inefficiencies reflect the fact that the catalysts work poorly over the solar spectral range. Although some element families (alkaline earth metals) offer promising results, a huge effort was still needed to make catalysts efficient enough for solar applications.
关键词： Efficiency,Zn1?xMxO,Nanocatalyst,Photocatalysis,Sol-gel process
更新于2025-09-10 09:29:36
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Crystal Structure Characterization of Thin Layer Zinc Oxide
摘要： In this research the characterization of the crystal structure of a thin layer of ZnO (zinc oxide) were synthesized by sol - gel method and spin coating deposited on a glass substrate. The samples were divided into three sol concentrations of 0.1, 0.3, 0.5 Molar and two deposition temperature is 350 °C, and 550 °C. UV-Vis. spectrophotometer results showed that in the spectrum of visible light (wavelength range 300-800 nm) has a transmittance value of which increases with increasing concentration and temperature deposition of zinc oxide, otherwise the value of the absorption and the band gap energy decreases with temperature. The transmittances value of the highest and lowest absorption was 93.5% and 0.03 is at a concentration of 0.1 M and zinc oxide deposition temperature of 550 °C, with a value of band gap energy of 2.98 eV. The XRD results showed that the zinc oxide crystal orientation in the field of 013 with a crystal grain size 14.4472 nm. SEM results showed the surface morphology of zinc oxide such as rod-like.
关键词： ZnO,sol-gel method,thin layer,crystal structure,optical properties,spin coating
更新于2025-09-10 09:29:36
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Influence of crosslinker structure on performance of functionalised organic-inorganic hybrid sol-gel coating
摘要： This research aimed to investigate the influence of the co-condensation of the three different organofunctional trialkoxysilane precursors with two different crosslinkers, i.e. tetraethoxysilane or organocyclotetrasiloxane on the performance and the washing fastness of this multicomponent multifunctional sol-gel coating on cellulose fibres. To this aim, a three-component 1H,1H,2H,2H-perfluorooctyltriethoxysilane (SiF), 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (SiQ) and P,P-diphenyl-N-(3-(trimethoxysilyl)propyl) phosphinic amide (SiP) in equimolar sol mixture (MC), which included or combination with organocyclotetrasiloxane 2,4,6,8-tetrakis(2-(diethoxy(methyl)silyl)ethyl)-2,4,6,8-tetramethyl–cyclotetrasiloxane (T4) as crosslinkers, was applied to the cotton fibres by a pad-dry-cure process. The functional properties of the coated samples before and after repeated washing were investigated by the water ? (W) and n-hexadecane ? (C16) static contact angle as well as water sliding (roll-off) (α) angle measurements. The inclusion of both TEOS and T4 into the MC sol increased the hydrophobic affect and simultaneously decreased the oleophobic effect of the MC coating. These phenomena were more pronounced for higher concentration of TEOS and T4 crosslinker. The inclusion of T4 into the MC sol improved the coating washing fastness to a significantly higher extent than the inclusion of TEOS, with respect to the applied concentrations.
关键词： crosslinker structure,organic-inorganic hybrid,oleophobic,hydrophobic,sol-gel coating,washing fastness
更新于2025-09-10 09:29:36
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Modifications in structural, optical and electrical properties of nanocrystalline CdO: role of sintering temperature
摘要： Present report deals with the synthesis of nanocrystalline cadmium oxide (CdO) using low-cost acetate precursor based modified sol–gel technique. Final product was sintered at different temperatures and studied for their structural, optical and electrical properties. In this present work, we report the sintering temperature-dependent structural, optical and electrical properties of nanocrystalline cadmium oxide (CdO) grown by cost effective sol–gel method. Structural properties of CdO materials were investigated by X–ray diffraction (XRD) which reveals the crystalline phase of the samples without any detectable impurity within the range of measurements. Crystallite size (CS), calculated using Scherer’s formula, is found in the range of nanometer (<100 nm) and increases with increasing sintering temperature. Average crystallite size of all CdO nanocrystals were estimated using the William–Hall (W–H) plots from XRD patterns. Furthermore, transmission electron microscopy (TEM) images were captured to check the crystallinity and particle growth of the samples. The optical properties of nanocrystalline CdO were studied by using UV–Visible (UV–Vis) absorption spectrum. High absorption has been observed for nanocrystalline CdO sintered at lower temperatures. The band gap of nanocrystalline CdO was calculated by using Tauc’s law where band gap increases with increasing sintering temperature. The electrical properties of the samples were studied by performing dielectric and AC conductivity measurements. It is observed that dielectric constant decreases with increase in frequency and sintering temperature. Variation in AC conductivity with light and sintering temperature has been discussed in detail.
关键词： Nanocrystalline,Photoconduction,Sol–gel synthesis,Sintering temperature
更新于2025-09-09 09:28:46