Microwave Synthesis of Nanoporous Materials

aThis paper reports on a new ozone gas sensor based on a-Ag 2 WO 4 nanorod-like structures. Electrical resistance measurements proved the efficiency of a-Ag 2 WO 4 nanorods, which rendered good sensitivity even for a low ozone concentration (80 ppb), a fast response and a short recovery time at 300 C, demonstrating great potential for a variety of applications.Metal semiconducting oxides have drawn the interest of many researchers due to their wide range of applications, especially as gas sensing materials. 1-5 Among them, one-dimensional (1-D) semiconductor nanostructures have been proposed as very interesting materials, especially as gas sensor devices.6-12 It is well known that several technological applications of nanostructured materials are directly related to the morphology, particle size, crystalline phase and activity of specic crystalline planes strictly dependent on synthesis methods. 4,[13][14][15] In particular, the relationship between morphology and gas sensing properties has been well established. 4,16,17Tungsten-based oxides are an important class of materials that display wide potential functional properties, 18-20 speci-cally the silver tungstate (Ag 2 WO 4 ) compound, which can exhibit three different structures: a-orthorhombic, b-hexagonal, and g-cubic.21-25 Recently, our research group reported a detailed study of the synthesis, structural and optical properties of hexagonal nanorod-like elongated a-Ag 2 WO 4 nanocrystals obtained by different methods. 26-28Ozone (O 3 ) is an oxidizing gas used in many technological applications in different areas, such as the food industry, drinking-water treatment, medicine, microelectronic cleaning processes, and others.29,34-39 For example, ozone has been employed as a powerful drinking-water disinfectant and oxidant. 34,35,40 On the other hand, when the ozone level in an atmosphere exceeds a certain threshold value, the exposure to this gas becomes hazardous to human health and can cause serious health problems (e.g. headache, burning eyes, respiratory irritation and lung damage).34,41 The European Guidelines (2002/3/EG) recommend avoiding exposure to ozone levels above 120 ppb.41 Such arguments support the requirement for the determination and continuous monitoring of ozone levels. 3,29,41Gas sensing properties are evaluated in terms of operating temperature, sensitivity, response time, recovery time and stability.29-33 SnO 2 , In 2 O 3 and WO 3 compounds have been considered the most promising ozone gas sensors. 29-33To the best of our knowledge, to date the gas sensing properties of a-Ag 2 WO 4 nanocrystals have never been evaluated.Here, we report the sensing properties of 1-D a-Ag 2 WO 4 nanorod-like structures obtained by the microwave-assisted hydrothermal (MAH) method.42-46 Because of such properties, nanorods are potential candidates for practical applications as ozone gas sensors.The crystalline phase of the as-obtained a-Ag 2 WO 4 sample was analyzed by X-ray diffraction measurement and all reec-tions were indexed to an orthorhombic struc...

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“…[42][43][44][45][46] Because of such properties, nanorods are potential candidates for practical applications as ozone gas sensors.…”

Section: -33mentioning

confidence: 99%

A novel ozone gas sensor based on one-dimensional (1D) α-Ag₂WO₄ nanostructures

et al. 2014

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“…34,35 Microwave method has also shown positive effects of narrow particle size distribution 36,37 and facile morphology control. 38,39 The microwave irradiation has been applied for the synthesis of metal-organic frameworks also.…”

Section: Introductionmentioning

confidence: 99%

Facile Syntheses of Metal-organic Framework Cu₃(BTC)₂(H₂O)₃under Ultrasound

Khan¹,

Jhung

2009

Bulletin of the Korean Chemical Society

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Cu-BTC[Cu3(BTC)2(H2O)3, BTC = 1,3,5-benzenetricarboxylate], one of the most well-known metal-organic framework materials (MOF), has been synthesized under atmospheric pressure and room temperature by using ultrasound. The Cu-BTC can be obtained in 1 min in the presence of DMF (N,N-dimethylformamide), suggesting the possibility of continuous production of Cu-BTC. Moreover, the surface area and pore volume show that the concentration of DMF is important for the synthesis of Cu-BTC having high porosity. The morphology and phase also depend on the concentration of DMF : Cu-BTC cannot be obtained at room temperature in the absence of DMF and aggregated Cu-BTC (with low surface area) is produced in the presence of high concentration of DMF. It seems that the deprotonation of benzenetricarboxylic acid by base (such as DMF) is inevitable for the room temperature syntheses.

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“…Numerous studies have been published on applications of microwave heating for nanomaterials synthesis. 29 Low microwave processing 30-32 temperature (95 • C) for about half an hour is used. No organic solvent is used.…”

mentioning

confidence: 99%

Green synthesis of tunable Cu(In1−xGax)Se2 nanoparticles using non-organic solvents

Juhaiman¹,

Scoles²,

Kingston³

et al. 2010

Green Chem.

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A green synthesis route of Cu(In 1-x Ga x )Se 2 nanoparticles with variable Ga content is described in this report for the first time. Only water and a minimum amount of energy input are used. Heating appropriate amounts of Cu, In, Ga and Se dispersed in an aqueous solution containing mercapto-acetic acid in a microwave oven gives rise to small and uniform nanoparticles. These new materials have been characterized to confirm composition, geometrical and structural properties. Transmission electron microcopy (TEM) confirmed size distribution around 4 nm. XRD confirmed the chalcopyrite structure with an average crystallite size of 3 nm. Atomic concentration and oxidation states of the different elements have been investigated using X-ray photoelectron spectroscopy (XPS). UV-visible absorption characterization confirmed the tunable optical properties of these materials. The proposed synthesis is scalable for commercial production with minimal environmental impact.

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Microwave Synthesis of Nanoporous Materials

Cited by 589 publications

References 152 publications

A novel ozone gas sensor based on one-dimensional (1D) α-Ag₂WO₄ nanostructures

A novel ozone gas sensor based on one-dimensional (1D) α-Ag₂WO₄ nanostructures

Facile Syntheses of Metal-organic Framework Cu₃(BTC)₂(H₂O)₃under Ultrasound

Green synthesis of tunable Cu(In1−xGax)Se2 nanoparticles using non-organic solvents

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Microwave Synthesis of Nanoporous Materials

Cited by 589 publications

References 152 publications

A novel ozone gas sensor based on one-dimensional (1D) α-Ag2WO4 nanostructures

A novel ozone gas sensor based on one-dimensional (1D) α-Ag2WO4 nanostructures

Facile Syntheses of Metal-organic Framework Cu3(BTC)2(H2O)3under Ultrasound

Green synthesis of tunable Cu(In1−xGax)Se2 nanoparticles using non-organic solvents

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A novel ozone gas sensor based on one-dimensional (1D) α-Ag₂WO₄ nanostructures

A novel ozone gas sensor based on one-dimensional (1D) α-Ag₂WO₄ nanostructures

Facile Syntheses of Metal-organic Framework Cu₃(BTC)₂(H₂O)₃under Ultrasound