A strategic approach for preparation of oxide nanomaterials

Rao, K. Yellareswar; Mahesh, Krishnamurthy; Kumar, Sundeep

doi:10.1007/bf02711166

Cited by 44 publications

(28 citation statements)

References 16 publications

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“…Sol-gel methods and some solvothermal methods produce poorly crystalline particles and require an additional crystallization step at high temperatures, giving rise to highly agglomerated ZrO2 NCs. 5,[14][15][16][17][18][19] Other methods suffer from the formation of mixed ZrO2 phases 5,20 and in general high temperatures and/or long reaction times 2,4,9,21 are required. These drawbacks depend on a combination of different factors: the selected synthesis method, presence or absence of pressure, difference in precursor solution or pH… One of the most appealing synthesis routes was introduced by Niederberger et al and uses a solvothermal autoclave method in benzyl alcohol to create a variety of crystalline metal oxide NCs (ZrO2, HfO2, In2O3, Ga2O3 …) at moderate temperatures.…”

Section: Introductionmentioning

confidence: 99%

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Keukeleere¹,

Roo

Lommens³

et al. 2015

Inorg. Chem.

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ABSTRACT:In this work, ZrO2 nanocrystals (NCs) are synthesized via a solvothermal treatment in benzyl alcohol, which is an established method for the synthesis of many metal oxide nanocrystals. We found that the use of microwave heating allows for a reduction in reaction time from 2 days in the autoclave to merely 4 hours in the microwave. Furthermore, we were able to tune the crystallographic phase from pure cubic to pure monoclinic zirconia by changing the reaction mechanism through the use of a different zirconium precursor. Via GC-MS measurements we found that the release of a strong acid during synthesis controls the key mechanism behind the control over crystal phase formation. The as-synthesized ZrO2 NCs (cubic or monoclinic) are small in size (3 -10 nm), yet aggregated. However, aggregrate-free NCs are generated through a surface-functionalization with carboxylic acid ligands, providing stabilization in apolar solvents via steric hindrance. Solution 1 H NMR was used to study the details of this post-modification step and the surface chemistry of the resulting aggregate-free NCs. This led to the conclusion that not only a different crystal structure but also a different surface chemistry is obtained depending on the precursor composition.

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Section: Introductionmentioning

confidence: 99%

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Keukeleere¹,

Roo

Lommens³

et al. 2015

Inorg. Chem.

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“…In literature, there are large number of reports for the synthesis of nanostructured ZnO such as precipitation/mechanical milling [21], microemulsion [22], ultrasonic radiation [23], microwave irradiation [24], solution combustion, microwave assisted solvothermal [25] and sol-gel method [26]. However, in recent years, the electrochemical method of synthesis of nanosized metal oxide powder and films have acquired a considerable interest because of its simplicity, low operating temperature and viability in commercial production.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Synthesis and Photocatalytic Property of Zinc Oxide Nanoparticles

Chandrappa

Venkatesha

2012

Nano-Micro Lett.

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Zinc oxide (ZnO) nanoparticles of varying sizes (20, 44 and 73 nm) have been successfully synthesized by a hybrid electrochemical-thermal method using aqueous sodium bicarbonate electrolyte and sacrificial Zn anode and cathode in an undivided cell under galvanostatic mode at room temperature. The as-synthesized product was characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Scanning electron microscopy along with Energy dispersive analysis of X-ray (SEM/EDAX), Transmission electron microscopy (TEM), Ultra Violet -Diffuse reflectance spectroscopic methods (UV-DRS). and UV-DRS spectral methods. The as-synthesized compound were single-crystalline and Rietveld refinement of calcined samples exhibited hexagonal (Wurtzite) structure with space group of P63mc (No.186). The band gaps for synthesized ZnO nanoparticles were 3.07, 3.12 and 3.13 eV, respectively, based on the results of diffuse reflectance spectra (DRS). The electrochemically synthesized ZnO powder was used as photocatalysts for UV-induced degradation of Methylene blue (MB). Photodegradation was also found to be function of exposure time and dye solution pH. It has been found that as-synthesized powder has excellent photocatalytic activity with 92% degradation of MB, indicating ZnO nanoparticles can play an important role as a semiconductor photocatalyst.

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“…Therefore, it can be assumed that diethyl ether molecules are not decomposed under microwave irradiation. Additionally, during the microwave synthesis of oxides, K. J. Rao et al [12] reported the formation of diethyl ether molecules by condensation of alcohol molecules. Moreover, MS-coupled DTA/TG-investigations on the dry aluminium alkoxy fluoride clearly showed the formation of diethyl ether and water as result of Lewis acid (Al 3 + ) induced alcohol condensation.…”

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confidence: 98%

Coupling Sol–Gel Synthesis and Microwave‐Assisted Techniques: A New Route from Amorphous to Crystalline High‐Surface‐Area Aluminium Fluoride

Dambournet

Eltanamy

Vimont

et al. 2008

Chemistry A European J

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A non-aqueous sol-gel Al-based fluoride has been subjected to the microwave solvothermal process. The final material depends on the temperature heat treatment used. Three types of material have been prepared: 1) for low temperature heat treatment (90 degrees C) X-ray amorphous alkoxy fluoride was obtained; 2) for the highest temperature used (200 degrees C) the metastable form beta-AlF3 was obtained with a very large surface area of 125 m2 g(-1). The mechanism of the amorphous=crystalline transformation has been rationalised by the occurrence of a decomposition reaction of the gel fluoride induced by the microwave irradiation. 3) Finally, at intermediate temperature (180 degrees C) a multi-component material mixture exhibiting a huge surface area of 525 m2 g(-1) has been obtained and further investigated after mild post-treatment fluorination using F2 gas. The resulting aluminium-based fluoride still possesses a high-surface-area of 330 m2 g(-1). HRTEM revealed that the solid is built from large particles (50 nm) identified as alpha-AlF3, and small ones (10 nm), relative to an unidentified phase. This new high-surface-area material exhibits strong Lewis acidity as revealed by pyridine adsorption and catalytic tests. By comparison with other materials, it has been shown that whatever the composition/structure of the Al-based fluoride materials, the number of strong Lewis acid sites is related to the surface area, highlighting the role of surface reconstruction occurring on a nanoscopic scale on the formation of the strongest Lewis acid sites.

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A strategic approach for preparation of oxide nanomaterials

Cited by 44 publications

References 16 publications

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Electrochemical Synthesis and Photocatalytic Property of Zinc Oxide Nanoparticles

Coupling Sol–Gel Synthesis and Microwave‐Assisted Techniques: A New Route from Amorphous to Crystalline High‐Surface‐Area Aluminium Fluoride

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A strategic approach for preparation of oxide nanomaterials

Cited by 44 publications

References 16 publications

Fast and Tunable Synthesis of ZrO2 Nanocrystals: Mechanistic Insights into Precursor Dependence

Fast and Tunable Synthesis of ZrO2 Nanocrystals: Mechanistic Insights into Precursor Dependence

Electrochemical Synthesis and Photocatalytic Property of Zinc Oxide Nanoparticles

Coupling Sol–Gel Synthesis and Microwave‐Assisted Techniques: A New Route from Amorphous to Crystalline High‐Surface‐Area Aluminium Fluoride

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Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence