Sol-Gel Synthesis of Nanocrystalline Ni-Ferrite and Co-Ferrite Redox Materials for Thermochemical Production of Solar Fuels

2014 ◽  
Vol 1675 ◽  
pp. 203-208 ◽  
Author(s):  
Rahul R. Bhosale ◽  
Ivo Alxneit ◽  
Leo L. P. van den Broeke ◽  
Anand Kumar ◽  
Mehak Jilani ◽  
...  
Keyword(s):  
Sol Gel ◽  
Solar Fuels ◽  
Bet Surface Area ◽  
Mixed Solution ◽  
Gel Formation ◽  
Thermochemical Cycles ◽  
X Ray ◽  
Thermogravimetric Analyzer ◽  
Sol Gel Synthesis

ABSTRACTIn this contribution, we report the synthesis and characterization of NixFe3-xO4 and CoxFe3-xO4 redox nanomaterials using sol-gel method. These materials will be used to produce solar fuels such as H2 or syngas from H2O and/or CO2 via solar thermochemical cycles (STCs). For the sol-gel synthesis of ferrites, the Ni, Co, Fe precursor salts were dissolved in ethanol and propylene oxide (PO) was added dropwise to the well mixed solution as a gelation agent to achieve gel formation. Freshly synthesized gels were aged, dried, and calcined by heating them to 600°C in air. The calcined powders were characterized by powder x-ray diffractometer (XRD), BET surface area, as well as scanning (SEM) and transmission (TEM) electron microscopy. Their suitability to be used in STCs for the production of solar fuels was assessed by performing several reduction/re-oxidation cycles using a thermogravimetric analyzer (TGA).

Sol-Gel Synthesis and Characterization of Nanocrystalline Bi4Ti3O12 Powders

2014 ◽  
Vol 997 ◽  
pp. 359-362 ◽  
Author(s):  
Chun Hong Ma ◽  
Xue Lin ◽  
Liang Wang ◽  
Yong Sheng Yan
Keyword(s):  
Phase Inversion ◽  
Bismuth Titanate ◽  
Sol Gel ◽  
Tetrabutyl Titanate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Synthesis ◽  
Source Materials

Nanocrystalline bismuth titanate (Bi4Ti3O12; BTO) powders were successfully prepared by the sol-gel method, using bismuth nitrate (Bi(NO3)3·5H2O) and tetrabutyl titanate (Ti(OC4H9)4) as source materials, acetic anhydride and ethanediol as solvents. The thermal decomposition and phase inversion process of the gel precursors were studied by using differential thermal analysis (DTA). The crystal structures and microstructures of BTO powders were investigated by using x-ray diffraction (XRD), and transmission electron microscope (TEM). The crystallization of amorphous bismuth titanate has been discussed. The effect of sintering temperature on the structure and morphology of BTO was investigated. At 644 oC and above, BTO powder undergoes a phase transformation from tetragonal to orthorhombic. At 900 oC, the purified orthorhombic BTO nanocrystals were obtained.

scholarly journals Synthesis and Characterization of Titania-Rice Husk Silica Composites as Photocatalyst

2015 ◽  
Vol 15 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Posman Manurung ◽  
Rudy Situmeang ◽  
Ediman Ginting ◽  
Indra Pardede
Keyword(s):  
Rice Husk ◽  
Sol Gel ◽  
Bet Surface Area ◽  
Synthesis And Characterization ◽  
Ultraviolet Rays ◽  
X Ray Diffraction ◽  
Titanium Butoxide ◽  
X Ray ◽  
Scanning Electron

This article describes the synthesis of titania-silica composites by a sol-gel method using a mixture of silica of rice husk and titanium butoxide sols. Microstructures were examined at calcination temperature in the range of 500 to 700 °C, with temperatures interval of 50 °C. The sintered catalysts were subsequently tested for photodegradation of methylene blue (MB) under ultraviolet and sunlight rays. Physical characteristics were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET). The XRD results did not show the presence of silica crystal phase in each sample. The results showed that the highest BET surface area of samples was obtained at the temperature of 650 °C. In sample calcined 500 °C, the activity of the catalyst on MB was relatively similar in both sunlight and ultraviolet rays.

Preparation and Characterization of Doped Nanometer TiO2

2007 ◽  
Vol 26-28 ◽  
pp. 649-652 ◽  
Author(s):  
Lin Yun Song ◽  
Yu Cheng Wu ◽  
Xiang Fen Lu
Keyword(s):  
Degradation Rate ◽  
Sol Gel ◽  
Complexing Agent ◽  
Gel Formation ◽  
X Ray Diffraction ◽  
Nano Tio2 ◽  
Doped Tio2 ◽  
X Ray ◽  
Different Temperatures

With Ti(OBu)4 as precursor, and HAC as complexing agent, pure and Fe-doped TiO2 gelatins were prepared by sol-gel method. During the process of gel formation, metal ions were dispersed into the porous TiO2 matrix. Then, powders of pure nano-TiO2 and Fe-doped nano-TiO2 were prepared by drying, grinding and calcining at different temperatures. The grain size and phase structure of pure and Fe-doped TiO2 after calcined at different temperatures, were studied by X-ray diffraction (XRD) and Beckman Coulter Sorption Analysis. The results showed that, the Fe3+-TiO2 had better photocatalytic activity in degradation rate of methyl orange under sunlight. The degradation rate was up to 93% as the system was placed under sunlight for 5 h. The optimum calcination temperature for the best catalytic activity was determined to be 500°C, and the mechanism was discussed.

scholarly journals Efficiency of TiO2 catalyst supported by modified waste fly ash during photodegradation of RR45 dye

2019 ◽  
Vol 26 (1) ◽  
pp. 292-300 ◽  
Author(s):  
Vanja Gilja ◽  
Zvonimir Katančić ◽  
Ljerka Kratofil Krehula ◽  
Vilko Mandić ◽  
Zlata Hrnjak-Murgić
Keyword(s):  
Fly Ash ◽  
Gas Adsorption ◽  
Sol Gel ◽  
Efficiency Evaluation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sol Gel Synthesis ◽  
Adsorption Desorption

AbstractThe waste fly ash (FA) material was subjected to chemical treatment with HCl at elevated temperature for a different time to modify its porosity. Modified FA particles with highest surface area and pore volume were further used as a support for TiO2 catalyst during FA/TiO2 nanocomposite preparation. The nanocomposite photocatalysts were obtained by in situ sol–gel synthesis of titanium dioxide in the presence of FA particles. To perform accurate characterization of modified FA and FA/TiO2 nanocomposite photocatalysts, gas adsorption-desorption analysis, X-ray diffraction, scanning electron microscopy, UV/Vis and Infrared spectroscopy were used. Efficiency evaluation of the synthesized FA/TiO2 nanocomposites was performed by following the removal of Reactive Red 45 (RR45) azo dye during photocatalytic treatment under the UV-A irradiation. Photocatalysis has been carried out up to five cycles with the same catalysts to investigate their stability and the possible reuse. The FA/TiO2 photocatalyst showed very good photocatalytic activity and stability even after the fifth cycles. The obtained results show that successfully modified waste fly ash can be used as very good TiO2 support.

Sol-gel synthesis and characterization of CuO–based nanosystems

2002 ◽  
Vol 737 ◽  
Author(s):  
Lidia Armelao ◽  
Davide Barreca ◽  
Manuel Bertapelle ◽  
Gregorio Bottaro ◽  
Cinzia Sada ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Copper Acetate ◽  
Dip Coating ◽  
Silica Matrix ◽  
Synthesis And Characterization ◽  
Host Matrix ◽  
X Ray ◽  
Sol Gel Synthesis

ABSTRACTThis paper is focused on the sol-gel synthesis and characterization of CuO-based nanosystems both in the form of supported films and as guest nanoclusters embedded in a silica matrix. In both cases copper acetate (Cu(CH3COO)2 · H2O) was used as Cu source and, for the CuO :SiO2 nanocomposite systems, tetraethoxysilane (Si(OC2H5)4, TEOS) was adopted as silica precursor. Films were obtained by a dip-coating procedure and subsequently treated in air between 100 and 900°C. The system evolution on thermal annealing was studied by X-ray photoelectron spectroscopy (XPS), Glancing-Incidence X-ray diffraction (GIXRD) and optical absorption. Irrespective of the processing conditions, the formation of tenorite (CuO) crystallites with nanometric dimension was observed. In the nanocomposite samples, copper was homogeneously distributed in the host matrix and stable CuO nanoclusters (φ ≈ 15 nm) were obtained.

Anomaly in thermal characterization of CaxMg1-xNb2O6 (x =0,0.4,0.6,1) towards LTCC applications

2012 ◽  
Vol 36 (1) ◽  
pp. 13-19
Author(s):  
Jyotirmayee Satapathy ◽  
M.V.Ramana Reddy
Keyword(s):  
Thermal Instability ◽  
Dielectric Material ◽  
Raw Materials ◽  
Sol Gel ◽  
Thermal Characterization ◽  
Extensive Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sol Gel Synthesis

Abstract Low temperature co-fired ceramics (LTCC), being the most advantageous technology related to the multilayer substrates for various applications, demands an extensive study of raw materials. In the present work, a series of CaxMg1−xNb2O6 (x =0, 0.4, 0.6, 1.0) were prepared using sol-gel synthesis route and sintered at a temperature of 900°C to study its applicability for LTCC technology. The phase formation has been confirmed using X-ray diffraction. Thermal properties like thermal conductivity and thermal expansion, which are very important aspects as the former defines the heat flow to avoid thermal instability in the layers and the latter provides the dimensional congruency of the dielectric material and the conductors, are studied here over high temperature range up to the firing temperature. Although the values are quite satisfactory from the application point view, the results have showed an anomaly over temperature. The anomalous thermal behavior was further analyzed using TG-DTA.

scholarly journals Sol-gel synthesis and study of neodymium substitution effects in Co-Al-Nd-O system with possible applications as novel inorganic pigments

2012 ◽  
Vol 10 (5) ◽  
pp. 1574-1583 ◽  
Author(s):  
Dalia Jonynaite ◽  
Darius Jasaitis ◽  
Rimantas Raudonis ◽  
Algirdas Selskis ◽  
Remigijus Juskenas ◽  
...  
Keyword(s):  
Sol Gel ◽  
Substitution Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sol Gel Process ◽  
New Compounds ◽  
Sol Gel Synthesis

AbstractIn the present work, the formation of cobalt aluminium spinel (CoAl2O4) as well as novel cobalt neodymium-aluminates with nominal compositions of CoAl1.75Nd0.25O4, CoAl1.5Nd0.5O4 and CoAlNdO4 by an aqueous sol-gel process and the sinterability of the products are investigated. The metal ions, generated by dissolving starting materials of metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the mixed metal ceramics. The phase purity of the synthesized compounds was characterized by powder X-ray diffraction analysis and infrared spectroscopy. The microstructural evolution and morphological features of the products were studied by scanning electron microscopy and atomic force microscopy, which together with the optical characterization of these new compounds showed that the sol-gel-derived materials could be successfully used as effective cobalt-based ceramic pigments.

scholarly journals Sol-gel Synthesis and Characterization of Lithium and Cerium Codoped Perovskite

2020 ◽  
Vol 9 (1) ◽  
pp. 17-24
Author(s):  
Katarina Mužina ◽  
Marija Tkalčević ◽  
Filip Brleković ◽  
Ivana Katarina Munda ◽  
Vilko Mandić ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Thermal Evolution ◽  
Sol Gel ◽  
Thermo Gravimetric Analysis ◽  
Calcium Nitrate ◽  
Gravimetric Analysis ◽  
X Ray ◽  
Sol Gel Synthesis ◽  
Thermally Treated

Perovskites are an important group of ceramic materials with a structural formula ABO3 and wide array of potential applications in electronics, superconductors, catalysis, etc. CaTiO3, by which the whole group was named for, is particularly significant due to its use in catalysis, but its photocatalytic activity is limited by a large band gap value (~3.5 eV). A possible solution is the substitution of A and B cations with foreign cations which causes the alteration of properties, including photocatalytic efficiency. The aim of this work was the sol-gel synthesis of lithium and cerium codoped CaTiO3, characterization of the prepared gel and ceramics obtained by its thermal treatment. Samples of codoped perovskite, Ca1-xLixCexTiO3, where x = 0, 0.01, 0.02, 0.03 and 0.04, were prepared and characterized using powder X–ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), differential thermal and thermo-gravimetric analysis (DTA-TGA), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Photocatalytic activity was evaluated through the study of methylene blue photocatalytic degradation. XRD analysis showed that the prepared samples consisted of calcium nitrate and titanium chelate. In accordance with the established thermal evolution path, all samples were thermally treated at 500 °C for 2 hours. Beside perovskite, Ca2Ti2O6 appeared as a secondary phase in all thermally treated samples. SEM analysis of thermally treated samples showed the presence of agglomerates of irregular morphology and the decrease of primary particles size with the increase of dopants concentration. The sample with x=0.04 showed an increased photocatalytic activity.

scholarly journals Synthesis and characterization of sol-gel derived monophasic mullite powder

Cerâmica ◽  
2020 ◽  
Vol 66 (379) ◽  
pp. 307-313
Author(s):  
A. Jana ◽  
D. Ray
Keyword(s):  
Sol Gel ◽  
Grain Morphology ◽  
Precursor Powder ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Heating Rates ◽  
X Ray ◽  
Heat Treated ◽  
Different Temperatures

Abstract High-purity microfine mullite precursor powder of stoichiometric chemical composition, 3Al2O3.2SiO2, was synthesized through the sol-gel route using aluminum isopropoxide and tetraethyl orthosilicate. The derived mullite precursor powder was characterized by BET surface area, particle size distribution, Fourier-transform infrared spectroscopy, thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy. Phase analysis of the precursor powder and calcined samples at different temperatures was done by XRD. Non-isothermal crystallization kinetics of mullite precursor was studied by TG-DTA in static air using heating rates of 5.0, 7.5, 10.0, 12.5, and 15 K.min-1. Grain morphology was studied by SEM. The results showed that synthesized mullite precursor powder possessed homogeneity of Al and Si components, and the amorphous precursor powder was converted to monophasic mullite crystal when heat-treated at 970 °C. Based on Flynn-Wall-Ozawa and Kissinger equations, the activation energy associated with the crystallization of mullite was determined to be 1189.8 and 1189.0 kJ.mol-1, respectively.

Sol-gel Synthesis, Magnetic and Structural Characterization of BaFe11.6–2xMxTixO19 (M=Co, Zn, Sn) Compounds.

2002 ◽  
Vol 755 ◽  
Author(s):  
G. Mendoza-Suárez ◽  
A.F. Fuentes ◽  
J.I. Escalante-García ◽  
O.E. Ayala-Valenzuela
Keyword(s):  
Magnetocrystalline Anisotropy ◽  
Sol Gel ◽  
Treatment Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Barium Ferrites ◽  
Crystallite Sizes ◽  
Sol Gel Synthesis

ABSTRACTSubstituted barium ferrites powders with Ti4+-M2+ (M = Co, Zn, Sn) cationic mixtures were prepared by a sol-gel route. The materials were heat-treated in the range 925–1000 °C and characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results showed that the effect of the substitution, x was to lower the coercivity (Hc), owing to the decrease of the magnetocrystalline anisotropy of the magnetoplumbite structure of the BaM. In this regard Sn-Ti substitutions tended to decrease Hc more rapidly than Zn-Ti and Ti-Co substitutions, in that order. Regarding the saturation magnetization (Ms), Zn-Ti mixtures showed slightly better Ms than Ti-Co substitutions; however, the Sn-Ti showed a more marked decrease as x increased. As revealed by SEM, the effect of the heat-treatment temperature was to increase the volume of multi-domain particles, following a Hc decrease due to grain coarsening. Contrarily, as a result of the improved crystallinity of the samples, as observed from the XRD peaks, Ms enhancement was recorded. Crystallite sizes decreased below 100 nm as x increased, although it was also dependent on the cationic mixture. In this respect Sn-Ti substitutions needed higher treatment temperatures to yield materials with adequate crystallinity and phase constitution.

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