Effect of annealing temperature on the structure of carbon encapsulated Fe<sub>3</sub>O<sub>4</sub> nanospheres

Shi, Weiping; Liu, W. F.; Chen, L.; Qin, Lei; Yang, Yongzhen; Liu, X. G.

doi:10.1039/c5ra19326e

Cited by 17 publications

(3 citation statements)

References 37 publications

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“…The effect of purification also decreased the intensity of Fe3O4 and Fe2O3, suggesting that it influences the magnetization of the purified products. Moreover, the purification effect of CMNs-ED impacts the reduced intensity of the amorphous carbon diffraction peak at 2θ 21.36° (Shi et al, 2015). The magnetic property of CMNs-ED before purification, CMNs-ED purified by water, and CMNs-ED purified by immersion in toluene followed by annealing treatment was investigated with a vibrating sample magnetometer (VSM).…”

Section: Resultsmentioning

confidence: 99%

Purification of Carbon-Based Magnetic Nanoparticles (CMNs) Produced by Submerged Arc Discharge in Liquid Ethanol/Ethylenediamine

Mayasari

Kuswari

Lestari

et al. 2021

Molekul

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Surface modification of covalently amine-attached carbon-based magnetic nanoparticles (CMNs) can be produced quite simply in submerged arc discharge using the amine-containing liquid medium ethylenediamine (ED), resulting in CMNs-ED. However, after the arc discharge processing, the resulting nanoparticles possibly contain physically absorbed amine-containing molecules from a liquid medium on the particle surface. To remove the non-covalently bound molecules, a purification process is required. In this study, the purification was conducted using polar and non-polar solvents following the synthesis process. The surface property was initially characterized by a dispersion test in water, showing that CMNs-ED purified by water have better dispersion than CMNs produced in ethanol alone, CMNs-ED before purification, and CMNs-ED after purification by immersion in toluene. Before and after purification, the diffraction pattern showed definitive peaks corresponded to the crystal planes of C(002), Fe3C(220), and Fe3O4(311) at 26.51°, 44.65°, and 35.42°, respectively. The amine functional group on the nanoparticles before purification thought to come from decomposed ethylenediamine assigned by the vibration peaks appeared at a wavenumbers ~3400 cm-1 and 1020-1220 cm-1, which corresponds to N-H and C-N, respectively. After purification, the vibration peaks of amine groups were still observable, indicating that the amine groups were still covalently attached to the nanoparticles. Magnetic analysis showed that CMNs before and after purification have superparamagnetic properties, with the magnetic saturation value around 10-17 emu/g. The electron microscope images show that the CMNs-ED before purification have a spherical form with a diameter larger than CMNs-ED after purification.

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Section: Resultsmentioning

confidence: 99%

Purification of Carbon-Based Magnetic Nanoparticles (CMNs) Produced by Submerged Arc Discharge in Liquid Ethanol/Ethylenediamine

Mayasari

Kuswari

Lestari

et al. 2021

Molekul

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“…The annealing temperature usually improves the surface pore structure of CNSs effectively, while easily causing the thermal cracking of surface oxygen-containing functional groups. − For the purpose of constructing abundant pore structure on the surface and making no effect on the subsequent grafting reaction, four different annealing temperatures were investigated combining Fourier transform infrared (FT-IR) analysis with BET result. Figure S1 displays the FT-IR spectra of CNS and PCNS at different annealing temperatures.…”

Section: Resultsmentioning

confidence: 99%

Selective Removal of Thiophene Using Surface Molecularly Imprinted Polymers Based on β-Cyclodextrin Porous Carbon Nanospheres and Polycarboxylic Acid Functional Monomers

Hua

Zhao

et al. 2019

Energy Fuels

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For the effective removal of thiophene, a novel surface molecularly imprinted polymer (SMIP/MA@PCNS) was fabricated using porous carbon nanospheres (PCNS-5) as the support matrix and maleic acid (MA) as the functional monomer. Benefiting from the special amphiphilic properties of β-cyclodextrin as the carbon source, PCNS-5 exhibited good dispersion, uniform nanoscale sphere, and high specific surface area, which favored the rapid adsorption rate. Based on the intermolecular hydrogen bonds existing between carboxylic acid functional groups and thiophene, adsorption performances of different unsaturated polycarboxylic acids were investigated systematically. The results revealed that the optimal functional monomer was MA instead of the conventional methacrylic acid. Accordingly, SMIP/MA@PCNS was successfully applied to the direct removal of thiophene in the oil, reaching remarkable sulfur adsorption capacity (22.6 mg S g −1 ) within 120 min. Moreover, SMIP/MA@PCNS could selectively remove thiophene (16.2 mg S g −1 ) in the presence of structural analogues (3methylthiophene, benzene, and cyclopentane) and exhibited an excellent regenerability with nice structural ability. These results indicated that SMIP/MA@PCNS possessed great promise in the desulfurization field.

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“…Earlier, we have shown that upon annealing in vacuum, oleic acid coated Fe 3 O 4 nanoparticles get reduced into metallic a-Fe at 500°C and into anti-ferromagnetic FeO phases at 700°C. 32 Recently, Shi et al 45 showed that the structure of carbon encapsulated individual Fe 3 O 4 nanoparticles under inert annealing conditions is stable up to 600°C. Indeed, carbon encapsulated Fe 3 O 4 reduced into Fe and Fe 3 C at 700°C due to carbothermic reduction process.…”

Section: Resultsmentioning

confidence: 99%

Superior thermal stability of polymer capped Fe₃O₄ magnetic nanoclusters

2017

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In general, the technologically important ferrites nanoparticles, magnetite and maghemite, are converted from cubic to the more stable rhombohedral structure above 500°C-700°C under air/vacuum/inert atmosphere. Here, we report, the superior thermal stability of polymer capped Fe 3 O 4 (PCIO) nanocluster (synthesized using microwave-assisted polyol approach) up to 1000°C under vacuum and inert atmosphere. Raman spectra of post annealed PCIO nanoclusters show the

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Effect of annealing temperature on the structure of carbon encapsulated Fe₃O₄ nanospheres

Abstract: Yolk–shell structured Fe3O4@C was obtained at 600 °C. A possible evolution mechanism of core–shell to yolk–shell Fe3O4@C is elaborated.

Cited by 17 publications

References 37 publications

Purification of Carbon-Based Magnetic Nanoparticles (CMNs) Produced by Submerged Arc Discharge in Liquid Ethanol/Ethylenediamine

Purification of Carbon-Based Magnetic Nanoparticles (CMNs) Produced by Submerged Arc Discharge in Liquid Ethanol/Ethylenediamine

Selective Removal of Thiophene Using Surface Molecularly Imprinted Polymers Based on β-Cyclodextrin Porous Carbon Nanospheres and Polycarboxylic Acid Functional Monomers

Superior thermal stability of polymer capped Fe₃O₄ magnetic nanoclusters

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Effect of annealing temperature on the structure of carbon encapsulated Fe3O4 nanospheres

Abstract: Yolk–shell structured Fe3O4@C was obtained at 600 °C. A possible evolution mechanism of core–shell to yolk–shell Fe3O4@C is elaborated.

Cited by 17 publications

References 37 publications

Purification of Carbon-Based Magnetic Nanoparticles (CMNs) Produced by Submerged Arc Discharge in Liquid Ethanol/Ethylenediamine

Purification of Carbon-Based Magnetic Nanoparticles (CMNs) Produced by Submerged Arc Discharge in Liquid Ethanol/Ethylenediamine

Selective Removal of Thiophene Using Surface Molecularly Imprinted Polymers Based on β-Cyclodextrin Porous Carbon Nanospheres and Polycarboxylic Acid Functional Monomers

Superior thermal stability of polymer capped Fe3O4 magnetic nanoclusters

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Effect of annealing temperature on the structure of carbon encapsulated Fe₃O₄ nanospheres

Superior thermal stability of polymer capped Fe₃O₄ magnetic nanoclusters