scholarly journals Photocatalytic activity of CaTaO2N nanocrystals obtained from a hydrothermally synthesized oxide precursor

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Specific Surface ◽  
Morphological Properties ◽  
Soft Chemistry ◽  
Co Catalyst ◽  
Surface Areas ◽  
Oxide Precursor ◽  
Photocatalytic Activities ◽  
Specific Surface Areas

Highly crystalline CaTaO2N nanoparticles possessing large specific surface areas were investigated as photocatalysts for the decomposition of methyl orange. Two different Ca2Ta2O7 precursors were synthesized by classical solid state synthesis and a hydrothermal soft-chemistry approach, respectively. In both cases, nitridation was carried out by thermal ammonolysis. The obtained CaTaO2N samples were compared with respect to their optical, thermal and morphological properties as well as their photocatalytic activities. In particular, the influence of ammonolysis temperature on the photocatalytic properties was studied. Using hydrothermally synthesized Ca2Ta2O7, phase pure CaTaO2N was obtained already at a relatively low ammonolysis temperature of 860 °C. Morphological investigations show that the CaTaO2N samples from the hydrothermally synthesized precursor consist of single-crystalline particles of 45 to 70 nm diameter with high specific surface areas between 12 and 19 m2 g-1, depending on ammonolysis temperature. A considerable photocatalytic activity for methyl orange degredation was found for the nanoscaled CaTaO2N particles prepared at lower ammonolysis temperatures. Using CoOx as co-catalyst, a further strong enhancement of the methyl orange decomposition by a factor 5-10 was achieved.

Hydrothermal Preparation and Photocatalytic Activity of Different Morphology Titania

2012 ◽  
Vol 510 ◽  
pp. 569-574 ◽  
Author(s):  
Huai Yuan Wang ◽  
Yan Ji Zhu ◽  
Zhen Yu ◽  
You Zhuang Zhu ◽  
Ying Chen
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Specific Surface ◽  
Photocatalytic Degradation ◽  
Anatase Phase ◽  
Tetrabutyl Titanate ◽  
Hydrothermal Preparation ◽  
Surface Areas ◽  
Template Free ◽  
Specific Surface Areas

TiO2 samples with various shapes like flake, nanofiber and large grain were synthesized by template-free hydrothermal method with rutile TiO2 or tetrabutyl titanate (Ti (OC4H9)4, TBOT) as precursor. Photocatalytic degradation performances were investigated by using methyl orange (MO) as modeling pollutant. The results shown that pure mesoporous anatase TiO2-Grain showed the highest photocatalytic activity (3.7 times higher than P25), which is due to a combinative effect of anatase phase and high specific surface areas. The bi-phase flaky TiO2 also have higher activity than P25. While, nanofiber with TiO2(B) phase has the lowest photocatalytic activity. The large sized TiO2 grain can be separated and recycled easily after reaction.

Solvothermal Synthesis of WO3 Photocatalysts and their Enhanced Activity

2011 ◽  
Vol 485 ◽  
pp. 283-286
Author(s):  
Yuji Kondo ◽  
Shinobu Fujihara
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Specific Surface ◽  
Tungsten Trioxide ◽  
Solvothermal Synthesis ◽  
Solvothermal Method ◽  
Spherical Particles ◽  
Hierarchical Architecture ◽  
Surface Areas ◽  
Specific Surface Areas

Tungsten trioxide (WO3) is known as a visible light responsive photocatalyst, but its photocatalytic activity is relatively low, as compared to that of anatase titanium dioxide (TiO2). To enhance the activity, high specific surface areas are necessary. In this study, WO3particles with a hierarchical architecture, which was assemblies of spherical particles 20 – 30 nm in diameter, were synthesized by the solvothermal method. The hierarchical WO3particles had high specific surface areas and their photocatalytic activity was found to be 2.5 times higher than that of the commercial WO3.

Three-dimensionally Hierarchical Bi2WO6 Architectures with Enhanced Photocatalytic Activity

NANO ◽  
2016 ◽  
Vol 11 (12) ◽  
pp. 1650135 ◽  
Author(s):  
Tianhua Chen ◽  
Hongbing Lu ◽  
Jinniu Zhang ◽  
Jianzhi Gao ◽  
Feng Yin ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Rhodamine B ◽  
Photocatalytic Performance ◽  
Ph Value ◽  
Precursor Solution ◽  
Structural Features ◽  
Oxygen Species ◽  
Surface Areas ◽  
Specific Surface Areas

Three-dimensionally hierarchical Bi2WO6 architectures have been produced via a facile and economical hydrothermal method without any template or surfactant. This architecture with flower-like morphology is assembled by numbers of intercrossed nanosheets. Moreover, different Bi2WO6 nanostructures including multilayered disks and irregular nanoplates can also be produced by simply adjusting the pH value of the precursor solution. Importantly, this kind of hierarchically structured Bi2WO6 architecture exhibits a much better photocatalytic activity in the photodegradation of rhodamine B than that of conventional Bi2WO6 multilayered disks and nanoplates. This enhanced photocatalytic performance is mainly attributed to the large specific surface areas, special structural features and high capability of absorbed oxygen species. The present work offers an effective approach for the further improvement of photocatalytic activity by designing a desirable micro/nanoarchitecture.

Photocatalytic Performance of SnO2 Prepared by Different Precipitants

2013 ◽  
Vol 331 ◽  
pp. 540-543
Author(s):  
Sheng Tian Huang ◽  
Jun Bo Zhong ◽  
Jian Zhang Li ◽  
Wei Hu
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Diffuse Reflectance ◽  
Photocatalytic Performance ◽  
Strong Dependence ◽  
Bet Surface Area ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Average Size

Parallel flow precipitation has been employed to prepare nanostructured SnO2. It is found that the specific surface areas and photocatalytic performance of SnO2 has a strong dependence on the kind of precipitant. The prepared photocatalysts were characterized by BET, XRD, UV-Vis diffuse reflectance and SEM. The results show that SnO2 prepared by NH3·H2O + (NH4)2CO3 has the highest BET surface area and the smallest crystal average size. SnO2 prepared by NH3·H2O + (NH4)2CO3 exhibits the best photocatalytic activity. The results of further experiments show that the specific surface area plays an important role in promotion of photocatalytic activity of SnO2 prepared by NH3·H2O + (NH4)2CO3.

Preparation of TiO2-based powders with high photocatalytic activities

1997 ◽  
Vol 12 (3) ◽  
pp. 607-609 ◽  
Author(s):  
Tomoko Kasuga ◽  
Masayoshi Hiramatsu ◽  
Masayoshi Hirano ◽  
Akihiko Hoson ◽  
Kyoko Oyamada
Keyword(s):  
Specific Surface ◽  
Sol Gel ◽  
Photocatalytic Property ◽  
Reflection Spectra ◽  
Gel Method ◽  
Sol Gel Method ◽  
Surface Areas ◽  
Infrared Reflection ◽  
Photocatalytic Activities ◽  
Specific Surface Areas

TiO2-based powders doped with a small amount of SiO2 were prepared by a sol-gel method and subsequently were heated to precipitate fine anatase crystals. Although the obtained powders have large specific surface areas (≈200 m2 · g−1), they showed poorer activity in a photocatalytic property than the undoped TiO2 powders which have the area of 50 m2 · g−1. The SiO2-doped TiO2 powders were treated chemically with aqueous NaOH. Infrared reflection spectra showed that the treatment reduced the amount of SiO2 in the powders. The photocatalytic property of the powders was extremely improved by the treatment, and the powders showed higher activity than the undoped TiO2 powders.

scholarly journals Ultrafine porous boron nitride nanofibers synthesized via a freeze-drying and pyrolysis process and their adsorption properties

RSC Advances ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 1253-1259 ◽  
Author(s):  
Jing Lin ◽  
Lulu Xu ◽  
Yang Huang ◽  
Jie Li ◽  
Weijia Wang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Specific Surface ◽  
Freeze Drying ◽  
Adsorption Properties ◽  
Pyrolysis Process ◽  
Surface Areas ◽  
Aspect Ratios ◽  
Large Pore ◽  
Specific Surface Areas

Ultrafine porous boron nitride nanofibers with high aspect ratios, high specific surface areas and large pore volumes has been synthesized in large quantity via a freeze-drying and post pyrolysis process.

scholarly journals Experimental Investigation of Coal Dust Wettability Based on Surface Contact Angle

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Gang Zhou ◽  
Han Qiu ◽  
Qi Zhang ◽  
Mao Xu ◽  
Jiayuan Wang ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Specific Surface ◽  
Coal Dust ◽  
Single Point ◽  
Contact Angles ◽  
Critical Surface ◽  
Volume Percentage ◽  
Surface Areas ◽  
Specific Surface Areas

Wettability is one of the key chemical properties of coal dust, which is very important to dedusting. In this paper, the theory of liquid wetting solid was presented firstly; then, taking the gas coal of Xinglongzhuang coal mine in China as an example, by determination of critical surface tension of coal piece, it can be concluded that only when the surface tension of surfactant solution is less than 45 mN/m can the coal sample be fully wetted. Due to the effect of particle dispersity, compared with the contact angle of milled coal particle, not all the contact angles of screened coal powder with different sizes have a tendency to increase. Furthermore, by the experiments of coal samples’ specific surface areas and porosities, it can be achieved that the volume of single-point total pore decreases with the gradual decreasing of coal’s porosity, while the ultramicropores’ dispersities and multipoint BET specific surface areas increase. Besides, by a series of contact angle experiments with different surfactants, it can be found that with the increasing of porosity and the decreasing of volume percentage of ultramicropore, the contact angle tends to reduce gradually and the coal dust is much easier to get wetted.

Facile Method To Synthesize Mesoporous Multimetal Oxides (ATiO3, A = Sr, Ba) with Large Specific Surface Areas and Crystalline Pore walls

2010 ◽  
Vol 22 (4) ◽  
pp. 1276-1278 ◽  
Author(s):  
Xiaoxing Fan ◽  
Ying Wang ◽  
Xinyi Chen ◽  
Ling Gao ◽  
Wenjun Luo ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Areas ◽  
Specific Surface Areas

Carbon Microspheres Prepared by High Internal Phase Emulsion Polymerization

2011 ◽  
Vol 239-242 ◽  
pp. 3105-3108
Author(s):  
Ming Xian Liu ◽  
Li Hua Gan ◽  
Jun Hu ◽  
Hong Lai Liu ◽  
Long Wu Chen
Keyword(s):  
Electron Microscopy ◽  
Specific Surface ◽  
Aqueous Phase ◽  
Apparent Density ◽  
Tween 80 ◽  
Carbon Microspheres ◽  
High Internal Phase Emulsion ◽  
Surface Areas ◽  
Internal Phase ◽  
Specific Surface Areas

In this paper, we present a novel approach for the synthesis of carbon microspheres via the polymerization of a high internal phase emulsion (HIPE). By using Span 80 and Tween 80 as emulsifiers, 1iquid paraffin as oil phase, and the mixture of resorcinol/formaldehyde (R/F) solution as aqueous phase, an O/W emulsion was obtained. This emulsion phase inverted to a W/O HIPE induced by ammonia which served as the polymerization catalyst. Carbon microspheres (CMs) were prepared by polymerization of the HIPE, followed by drying and carbonization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analyzer were used to characterize as-prepared CMs. The results indicate that, in case of 0.25 wt% ammonia of the HIPE, the diameters of CMs decreased from about 2 to 1 μm when the mass fraction of aqueous R/F decreased from 0.714 to 0.357; the apparent density and the specific surface areas of the CMs, however, did not change obviously, which are about 0.6 g/cm3and 200 m2/g, respectively. The dosage of ammonia has a significant influence on the morphology and properties of CMs. With increasing of the ammonia mass to 1 wt% of the HIPE, the resultant carbon materials comprise not only CMs, but also some carbon sheets; the apparent density of which increased to 0.9 g/cm3and the specific surface areas of which decreased to below 100 m2/g. In addition, the other parameters for CMs preparation were also investigated. It was found that the proper conditions were controlling the temperature of 303-333 K and the oil/aqueous phase mass ratio of 2.5:7.

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