scholarly journals Synthesis of Nanostructured TiO2 Microparticles with High Surface Area

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1512
Author(s):  
Lev Matoh ◽  
Boštjan Žener ◽  
Tina Skalar ◽  
Urška Lavrenčič Štangar
Keyword(s):  
Particle Size ◽  
Photocatalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Tio2 Particle ◽  
Nanostructured Tio2 ◽  
Degradation Rates

Hydrothermal reactions represent a simple and efficient method for the preparation of nanostructured TiO2 particles that could be of interest as photocatalysts or catalytic supports. Although the particle size is in the range of 2–5 µm, the nanostructures composing the particles ensure a large specific surface area with values above 100 m2/g. The effects of the different synthesis parameters on the morphology, photocatalytic activity, and stability of the prepared material were studied. The surface morphology of the prepared TiO2 powders was studied by scanning electron microscopy (SEM). To further characterize the samples, the specific surface area for different morphologies was measured and the photocatalytic activity of the prepared powders was tested by degrading model pollutants under UV irradiation. The results show that the initial morphology had little effect on the photocatalytic properties. On the other hand, the final calcination temperature significantly increased the degradation rates, making it comparable to that of P25 TiO2 (particle size 20–30 nm).

Effect of phase composition, morphology, and specific surface area on the photocatalytic activity of TiO2 nanomaterials

RSC Advances ◽  
2014 ◽  
Vol 4 (87) ◽  
pp. 47031-47038 ◽  
Author(s):  
Hao Cheng ◽  
Jingyu Wang ◽  
Yizhi Zhao ◽  
Xijiang Han
Keyword(s):  
Photocatalytic Activity ◽  
Phase Composition ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Tio2 Nanomaterials

TiO2-based nanomaterials could reach the maximal photoactivity when designing 0D/1D heterogenous structure with appropriate phase composition and high surface area.

scholarly journals MECHANOCHEMICAL SYNTHESIS OF CALCIUM TITANATE AND RESEARCH OF ITS PHOTOCATALYTIC ACTIVITY

2018 ◽  
Vol 59 (6) ◽  
pp. 83 ◽  
Author(s):  
Konstantin V. Ivanov ◽  
Alexandr V. Agafonov ◽  
Olyga V. Alexeeva
Keyword(s):  
Particle Size ◽  
Photocatalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Biological Tissues ◽  
Calcium Titanate ◽  
Ceramic Technology ◽  
X Ray Diffraction ◽  
X Ray

Recently much attention is paid to the synthesis and study of the properties of inorganic materials, based on alkaline earth titanates with a perovskite structure that have various polymorphic forms depending on the temperature. Calcium titatanat (CaTiO3) can be selected from the variety of perovskites because of its relatively high dielectric constant, unique photochemical properties, chemical stability, and compatibility with biological tissues, which leads to its application in microelectronics, photocatalysis and biomedicine as bone implants. In this paper, a solid-phase synthesis of calcium titanate was carried out by ceramic technology using mechanochemistry methods. This method allows to obtain calcium titanate directly by mechanochemical activation from the initial mixture of Ca (OH)2 and TiO2, which significantly reduces the energy consumption for its production. Structural changes in the synthesized material during calcination at 120 °C, 200 °C, 400 °C, 600 °C, and 800 °C were studied. The particle size and specific surface area of powders synthesized and calcined at 800 °C was measured by laser diffraction ("Analysette 22") and the low temperature (77K) nitrogen adsorption-desorption vapor, respectively. The phase composition of the obtained materials was studied by X-ray diffraction. It was found on the basis of studies of the particle size distribution that synthesized and calcined powders contain nanoparticles with sizes of 377 and 422 nm. The samples of CaTiO3 calcined at 120 °C and 800 °C have a mesoporous structure, the specific surface area was 46 and 7 m2/g, respectively, and average pore size in powders was 4 nm. It was found by the X-ray diffraction technique that the uncalcined sample contains admixtures of CaCO3 and TiO2 that can be removed completely at 600 °C.The photocatalytic activity of the synthesized material has been studied by the example of Rhodamine B dye decoloration on the calcium titanate calcined at 800°C. It was found that the decomposition degree of dye in solution was 77% for 80 min at a 6.7% shadow adsorption.

Effect of Solvothermal Treatment on Physical Properties of Nickel and Aluminum Based Oxide Powders Synthesized by Coprecipitation

2015 ◽  
Vol 820 ◽  
pp. 73-78
Author(s):  
Guilherme Luis Cordeiro ◽  
Walter Kenji Yoshito ◽  
Valter Ussui ◽  
Nelson Batista de Lima ◽  
Dolores Ribeiro Ricci Lazar
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
Nickel Content ◽  
High Surface Area ◽  
Aging Treatment ◽  
Catalytic Efficiency ◽  
Nickel Aluminate ◽  
Solvothermal Treatment

Improvements of the catalytic efficiency of nickel–aluminum oxides in reforming reactions for hydrogen production have been achieved by the development of synthesis processes that provide powders with high surface area. The reduction of the crystallization temperature is one of the procedures in this direction. In this work, the effect of solvothermal treatment on coprecipitated gels with 15 wt% nickel content in alumina matrix was evaluated. Powders were obtained by coprecipitation with and without treatment of gels under n-butanol vapor pressure at 150oC. Products were characterized by TG/DTA, X-ray diffraction, specific surface area measurements, scanning electron microscopy and laser beam scattering for granulometric distribution determination. The results showed that calcined powders have high specific surface area (ranging from 170 to 260 m2.g-1) and are composed by gamma alumina and nickel aluminate phases. Aging treatment did not promote hydroxides decomposition under solvothermal conditions, indicating the need of calcination step.

Ion-matching porous carbons with ultra-high surface area and superior energy storage performance for supercapacitors

2019 ◽  
Vol 7 (15) ◽  
pp. 9163-9172 ◽  
Author(s):  
Lifeng Zhang ◽  
Yu Guo ◽  
Kechao Shen ◽  
Jinghao Huo ◽  
Yi Liu ◽  
...  
Keyword(s):  
Energy Storage ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
High Specific Surface Area ◽  
Porous Carbons ◽  
Storage Performance

Polypyrrole (PPy)-derived porous carbons with an ion-matching micropore diameter exhibit ultra-high specific surface area and capacitance when used in supercapacitors.

scholarly journals Efficiency of solar water disinfection photocatalized by titanium dioxide of varying particle size

2007 ◽  
Vol 5 (3) ◽  
pp. 335-340 ◽  
Author(s):  
F. M. Salih ◽  
A. E. Pillay
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Tio2 Particle ◽  
Water Disinfection ◽  
Local Concentration ◽  
Bacterial Cells ◽  
Radical Interaction

Titanium dioxide photocatalysed water disinfection is induced by the interaction of light with TiO2, which generates highly reactive free hydroxyl radicals (OH•). These free radicals create lethal damage that leads to bacterial death. Normally, decreasing TiO2 particle size increases the area of light interaction. This may possibly increase the concentration of OH• generated and hence increases disinfection efficiency. Moreover, decreasing the particle size increases the force of attraction between the particles and cells, which could create aggregates that may contribute to the local OH• concentration. In the present investigation cells of Escherichia coli were used as the test microorganism, TiO2 as the photocatalyst and sunlight as the light source. Four different surface areas of TiO2 particles corresponding to 10, 50, 80–100 and ≥300 m2 g−1 were tested at a concentration of 1 g l−1. Disinfection efficiency increased with increasing the surface area producing a maximum between 80–100 m2 g−1 followed by a reduction at ≥300 m2 g−1. The reduction in the efficiency at this relatively high surface area was attributed to the increase in the local concentration of OH•. This increase may be high enough to initiate radical-radical interaction that would compete with bacterial cells and reduce the chance of bacterial cell-radical interaction taking place. Moreover, the phenomenon of TiO2 aggregation with bacterial cells plays an important role, and the extent of aggregation increases with decreasing particle size. Such aggregation could augment the concentration of OH• within the cell vicinity. This suggests that surface area is a key factor in determining the efficiency of disinfection, and that concentration is a vital factor.

scholarly journals Flame-made Ceria Nanoparticles

2002 ◽  
Vol 17 (6) ◽  
pp. 1356-1362 ◽  
Author(s):  
L. Mädler ◽  
W. J. Stark ◽  
S. E. Pratsinis
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
Acetic Acid Solution ◽  
High Surface Area ◽  
Flame Spray ◽  
Good Thermal Stability ◽  
Primary Particles ◽  
Stepped Surface

Flame spray pyrolysis (FSP) has been used to synthesize high-surface-area ceria from cerium acetate in acetic acid solution. With the addition of an iso-octane/2-butanol mixture to that solution, homogeneous CeO2 nanoparticles were obtained. The specific surface area of the powders ranged from 240 to 101 m2/g by controlling the oxygen dispersion and liquid precursor flow rates through the flame. Furthermore, for production rates from 2 to 10 g/h a constant average primary particle size could be obtained at selected process parameters. The ceria showed high crystallinity and primary particles with a stepped surface. The powder exhibited good thermal stability and conserved up to 40% of its initial specific surface area when calcinated for 2 h at 900 °C. This shows the potential of FSP made ceria for high-temperature applications as in three-way catalysts or fuel cells.

scholarly journals WO3Nanoplates Film: Formation and Photocatalytic Oxidation Studies

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Chin Wei Lai
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Oxidation Reaction ◽  
Photocatalytic Oxidation ◽  
Dye Degradation ◽  
Film Formation ◽  
High Surface ◽  
High Surface Area ◽  
Electrochemical Anodization

High surface area of tungsten oxide (WO3) nanoplates films was prepared via simple electrochemical anodization technique by controlling the fluoride content (NH4F) in electrolyte. The design and development of WO3-based nanostructure assemblies have gained significant interest in order to maximize specific surface area for harvesting more photons to trigger photocatalytic oxidation reaction. This study aims to determine the optimum content of NH4F in forming WO3nanoplates on W film with efficient photocatalytic oxidation reaction for organic dye degradation by utilizing our solar energy. The NH4F was found to influence the chemical dissolution and field-assisted dissolution rates, thus modifying the final morphological of WO3-based nanostructure assemblies film. It was found that 0.7 wt% of NH4F is the minimum amount to grow WO3nanoplates film on W film. The photocatalysis oxidation experimental results showed that WO3nanoplates film exhibited a maximum degradation of methyl orange dye (≈75%) under solar illumination for 5 hours. This behavior was attributed to the better charge carriers transportation and minimizes the recombination losses with specific surface area of nanoplates structure.

Metal Oxides (such as Al2O3 and TiO2) as Catalyst Supports for Hydrogen Release by Hydrolysis of Sodium Borohydride NaBH4

2010 ◽  
Vol 65 ◽  
pp. 209-214
Author(s):  
Ouardia Akdim ◽  
Umit Bilge Demirci ◽  
Philippe Miele
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Supported Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Active Phase ◽  
Hydrogen Release ◽  
Catalytic Systems ◽  
Hydrolysis Of

Hydrolysis of NaBH4 to release molecular hydrogen is today an intensely investigated reaction and most of the studies focus on the material used as catalyst. Among the various metals tested up to now, cobalt has soon showed to be the most attractive in terms of reactivity and cost. Nevertheless, in order to further decrease its cost by decreasing its amount as well as to increase its reactivity, cobalt has been dispersed over supports. The as-formed supported catalysts have showed to be more efficient. This is the topic of the present study. Herein it is showed that CoCl2 supported over an Al2O3 support with a specific surface area of 180 m2 g-1 is more reactive than CoCl2 supported over a high-surface-area activated carbon (780 m2 g-1), CoCl2 being in-situ reduced into the Co-based active phase. CoCl2-Al2O3 is besides as reactive as another CoCl2-Al2O3 catalyst, the latter support having a higher specific surface area (i.e. 250 m2 g-1). In fact, CoCl2-Al2O3 is more performing than neat CoCl2 whereas the latter has been often showed as being one of the best catalytic systems. To further gain in reactivity, a new, alternative strategy has been envisaged. The Al2O3 was mixed together with a controlled amount of another oxide, namely TiO2. The CoCl2- Al2O3-TiO2(20 wt%) was found to be more reactive than CoCl2-Al2O3. All of these reactivity data are reported and briefly discussed hereafter. Further studies are in progress to highlight the reasons of such improved reactivity.

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