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Makeswaran N, Kelly JP, Haslam JJ, McKeown JT, Ross MS, Ramana CV. Crystallization, Phase Stability, Microstructure, and Chemical Bonding in Ga 2O 3 Nanofibers Made by Electrospinning. ACS OMEGA 2022; 7:32816-32826. [PMID: 36120052 PMCID: PMC9476513 DOI: 10.1021/acsomega.2c05168] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 08/25/2022] [Indexed: 05/27/2023]
Abstract
We report on the crystal structure, phase stability, surface morphology, microstructure, chemical bonding, and electronic properties of gallium oxide (Ga2O3) nanofibers made by a simple and economically viable electrospinning process. The effect of processing parameters on the properties of Ga2O3 nanofibers were evaluated by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Thermal treatments in the range of 700-900 °C induce crystallization of amorphous fibers and lead to phase stabilization of α-GaOOH, β-Ga2O3, or mixtures of these phases. The electron diffraction analyses coupled with XPS indicate that the transformation sequence progresses by forming amorphous fibers, which then transform to crystalline fibers with a mixture of α-GaOOH and β-Ga2O3 at intermediate temperatures and fully transforms to the β-Ga2O3 phase at higher temperatures (800-900 °C). Raman spectroscopic analyses corroborate the structural evolution and confirm the high chemical quality of the β-Ga2O3 nanofibers. The surface analysis by XPS studies indicates that the hydroxyl groups are present for the as-synthesized samples, while thermal treatment at higher temperatures fully removes those hydroxyl groups, resulting in the formation of β-Ga2O3 nanofibers.
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Affiliation(s)
- Nanthakishore Makeswaran
- Centre
for Advanced Materials Research (CMR), University
of Texas at El Paso, 500 W University Ave, El Paso, Texas 79968, United
States
- Materials
Engineering Division, Lawrence Livermore
National Laboratory, 7000 East Avenue, Livermore, California 94550-5507, United States
| | - James P. Kelly
- Materials
Engineering Division, Lawrence Livermore
National Laboratory, 7000 East Avenue, Livermore, California 94550-5507, United States
| | - Jeffery J. Haslam
- Materials
Engineering Division, Lawrence Livermore
National Laboratory, 7000 East Avenue, Livermore, California 94550-5507, United States
| | - Joseph T. McKeown
- Materials
Science Division, Lawrence Livermore National
Laboratory, 7000 East
Avenue, Livermore, California 94550-5507, United States
| | - Michael S. Ross
- Materials
Engineering Division, Lawrence Livermore
National Laboratory, 7000 East Avenue, Livermore, California 94550-5507, United States
| | - C. V. Ramana
- Centre
for Advanced Materials Research (CMR), University
of Texas at El Paso, 500 W University Ave, El Paso, Texas 79968, United
States
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A Novel Method for Generating H2 by Activation of the μAl-Water System Using Aluminum Nanoparticles. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12115378] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A method is described for activation of the reaction of room temperature water with micron-scale aluminum particles (μAl) by the addition of poly(epoxyhexane)-capped aluminum nanoparticles (Al NPs). By themselves, Al NPs react vigorously and completely with water at ambient temperatures to produce H2. While pure μAl particles are unreactive toward water, mixtures of the μAl particles comprising 10 to 90% (by mass) of Al NPs, demonstrated appreciable hydrolytic activation. This activation is attributed to the reaction of the Al NPs present with water to produce a basic solution. Speciation modelling, pH studies, and powder X-ray diffraction analysis of the hydrolysis product confirm that the pH change is the key driver for the activation of μAl rather than residual heat from the exothermicity of Al NP hydrolysis. A mechanism is proposed by which the nonreactive aluminum oxide layer of the μAl is eroded under basic conditions. Mixtures 10% by mass of Al NPs can be used to produce the optimal quantity of H2.
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Dhara M, Rudra S, Mukherjee N, Jana T. Hollow polymer nanocapsules with a ferrocenyl copolymer shell. Polym Chem 2021. [DOI: 10.1039/d1py00590a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Hollow polymer nanocapsules consisting of ferrocenyl shell have been developed by crosslinking the polymer chains grafted over silica nanoparticles synthesized via one pot surface-initiated RAFT polymerization.
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Affiliation(s)
- Moumita Dhara
- School of Chemistry
- University of Hyderabad
- Hyderabad 500046
- India
| | - Somdatta Rudra
- School of Chemistry
- University of Hyderabad
- Hyderabad 500046
- India
| | | | - Tushar Jana
- School of Chemistry
- University of Hyderabad
- Hyderabad 500046
- India
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Klein T, Kickelbick G. Synthesis of submicron aluminum particles via thermal decomposition of alkyl aluminum precursors in the presence of metal seeds and their application in the formation of ruthenium aluminides. NANOTECHNOLOGY 2020; 31:265605. [PMID: 32160597 DOI: 10.1088/1361-6528/ab7ef5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Submicron Al particles can be used in energy materials, as reducing agents, or for the formation of aluminides. Their standard electrode potential and their reactivity towards oxygen makes their synthesis a challenging task. Here we present a thermal decomposition approach starting from triisobutylaluminium (TIBAL) as a precursor. This compound can be decomposed in refluxing diphenylether as a high-boiling solvent and in the presence of metallic nanoparticles of Ni, Ru or Ag acting as seeds. The resulting particles revealed sizes of around 100 nm. Passivation of the Al particles is possible in an optional second step after the synthesis by adding oleic acid resulting in the formation of organically capped Al particles. The suitability of these submicron particles for the synthesis of aluminides was studied by reacting the synthesized particles with Ru powders, resulting in the formation of the respective aluminide.
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Affiliation(s)
- Thomas Klein
- Inorganic Solid State Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany
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Nnaji N, Nwaji N, Mack J, Nyokong T. Corrosion Resistance of Aluminum against Acid Activation: Impact of Benzothiazole-Substituted Gallium Phthalocyanine. Molecules 2019; 24:molecules24010207. [PMID: 30626054 PMCID: PMC6337598 DOI: 10.3390/molecules24010207] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/03/2019] [Accepted: 01/04/2019] [Indexed: 11/27/2022] Open
Abstract
This study describes the adsorption behavior of organic inhibitors at the aluminum-HCl solution interface and their corrosion inhibition performance. The organic inhibitors employed are: 4-(benzo [d]thiazol-2ylthio)phthalonitrile (BTThio) and tetrakis[(benzo[d]thiazol-2-yl-thio)phthalo- cyaninato]gallium(III) chloride (ClGaBTThioPc). The corrosion behavior of these inhibitors is investigated using electrochemical and computational techniques. Open circuit potential results reveal predominant cathodic character for the mechanism of aluminum corrosion inhibition by the inhibitors. Inhibition efficiency values from potentiodynamic polarization measurements increase from 46.9 to 70.8% for BTThio and 59.7 to 81.0% for ClGaBTThioPc within the concentration range of 2 to 10 μM. Scanning electron microscopy (SEM) measurements reveal protection of the metal surface from acid attack, in the presence of the inhibitors and energy dispersive X-ray (EDX) measurements show that the most probable way by which the inhibitors protect the metal surface would be by shielding it from the corrosion attacks of Cl− from the acid. Quantum chemical parameters corroborate well with experimental findings.
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Affiliation(s)
- Nnaemeka Nnaji
- Centre for Nanotechnology Innovation, Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa.
| | - Njemuwa Nwaji
- Centre for Nanotechnology Innovation, Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa.
| | - John Mack
- Centre for Nanotechnology Innovation, Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa.
| | - Tebello Nyokong
- Centre for Nanotechnology Innovation, Department of Chemistry, Rhodes University, Grahamstown 6140, South Africa.
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