Structural and magnetic properties of Co Fe3−O4 versus Co/Fe molar ratio

Dippong, Thomas; Levei, Erika Andrea; Diamandescu, L.; Bibicu, I.; Leoștean, Cristian; Borodi, Gheorghe; Barbu–Tudoran, Lucian

doi:10.1016/j.jmmm.2015.06.055

Cited by 51 publications

(11 citation statements)

References 30 publications

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“…When the Co content is further increased, it can be seen that Fe0.5Co/NOMC includes two spinel phases, viz. CoxFe3−xO4 and Co3O4 (PDF#42-1467) [33,34]. Finally, Co/NOMC shows the characteristic spinel phase of Co3O4 (PDF#42-1467).…”

Section: Resultsmentioning

confidence: 99%

Efficient spinel iron-cobalt oxide/nitrogen-doped ordered mesoporous carbon catalyst for rechargeable zinc-air batteries

Wei

Tan

et al. 2021

Chinese Journal of Catalysis

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A robust oxygen-related electrocatalyst, composed of spinel iron-cobalt oxide and nitrogen-doped ordered mesoporous carbon (NOMC), was developed for rechargeable metal-air batteries. Electrochemical tests revealed that the optimal catalyst Fe0.5Co/NOMC exhibits superior activity with a half-wave potential of 0.89 V (vs. reversible hydrogen electrode) for the oxygen reduction reaction and an overpotential of 0.31 V at 10 mA cm −2 for the oxygen evolution reaction. For demonstration, the catalyst was used in the assembly of a rechargeable zinc-air battery, which exhibited an exceptionally high energy density of 820 Wh kg −1 at 100 mA cm −2 , a high power density of 153 mW cm −2 at 1.0 V, and superior cycling stability up to 432 cycles (144 h) under ambient air.

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Section: Resultsmentioning

confidence: 99%

Efficient spinel iron-cobalt oxide/nitrogen-doped ordered mesoporous carbon catalyst for rechargeable zinc-air batteries

Wei

Tan

et al. 2021

Chinese Journal of Catalysis

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“…The magnetic nanoparticles results in surface anisotropy, crystalline disorder, low particle-particle interaction, weakening of the exchange coupling energy and a significant decrease of Ms value [40]. This is explained based on the contribution of the non-magnetic PAM/PEG coating layer to the total magnetization, which means that the total magnetic behavior of the nanocomposites can be tuned and tailored depending on the coated layer [30].…”

Section: Resultsmentioning

confidence: 99%

Crystal structures and magnetic properties of polyethylene glycol/polyacrylamide encapsulated CoCuFe4O8 ferrite nanoparticles

et al. 2020

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Polymer-inorganic nanocomposites with systematized structure provide a novel composite material having complementary between the polymer and inorganic materials. A new CoCuFe 4 O 8 spinel ferrite was prepared by a modified citrate auto combustion technique. The formation of the core-shell structure by coating CoCuFe 4 O 8 nanoparticles (NPs) with Polyethylene glycol (PEG) or Polyacrylamide (PAM) was successfully proceeding. The X-ray diffraction analysis shows that the prepared sample crystallizes in a cubic crystal structure with the Fd3m space group. The structural changes are elucidated via diametrical size, lattice parameter, dislocation density and strain. The obtained data reveals that after coating with PEG/ PAM the crystallite size of CoCuFe 4 O 8 spinel ferrite nanoparticles decreases while, the dislocation density increases. The dislocation density provides more energy-friendly locations for nucleation, consequently, the crystallinity deteriorates and the crystal grains become finer. High-Resolution Transmission Electron Microscopy (HRTEM) images ratify that the spinel nanoparticles are embedded in the PEG/PAM matrix forming the core-shell structure. The measurements of the magnetic hysteresis loops assure that all prepared samples exhibit a hard ferrite nature with a coercivity ranging from 1525 to 1512 Oe. The decrease of the magnetic parameters of CoCuFe 4 O 8 /PEG-PAM can be explained on the basis of the contribution of the non-magnetic coating layer to the total magnetization. The total magnetic behavior of the nanocomposites can be tuned and tailored depending on the coating layers. Based on the obtained data, the formulated CoCuFe 4 O 8 decorated with PEG-PAM can be recognized as a promising functional material for applications in biomedicine. The enhanced magnetic properties make CoCuFe 4 O 8 /PEG-PAM a fitting candidate in the high-density recording.

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“…The oxide shell has a cubic inverse spinel structure (space group Fd3m) and forms during the slow air exposure for XRD and TEM experiments [25]. The shell is identified as magnetite Fe 3 O 4 for the elemental Fe NPs, and cobalt ferrite (Fe x Co 1-x ) 3 O 4 [26,27] for the Fe-Co nanoalloys. The STEM-EDX profiles in Figure 2e,f show that the Fe/Co ratio in the shell is similar to the core.…”

Section: Structure Morphology and Composition Of Fe-co Nanoalloysmentioning

confidence: 99%

CO2 Hydrogenation over Unsupported Fe-Co Nanoalloy Catalysts

et al. 2020

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The thermo-catalytic synthesis of hydrocarbons from CO2 and H2 is of great interest for the conversion of CO2 into valuable chemicals and fuels. In this work, we aim to contribute to the fundamental understanding of the effect of alloying on the reaction yield and selectivity to a specific product. For this purpose, Fe-Co alloy nanoparticles (nanoalloys) with 30, 50 and 76 wt% Co content are synthesized via the Inert Gas Condensation method. The nanoalloys show a uniform composition and a size distribution between 10 and 25 nm, determined by means of X-ray diffraction and electron microscopy. The catalytic activity for CO2 hydrogenation is investigated in a plug flow reactor coupled with a mass spectrometer, carrying out the reaction as a function of temperature (393–823 K) at ambient pressure. The Fe-Co nanoalloys prove to be more active and more selective to CO than elemental Fe and Co nanoparticles prepared by the same method. Furthermore, the Fe-Co nanoalloys catalyze the formation of C2-C5 hydrocarbon products, while Co and Fe nanoparticles yield only CH4 and CO, respectively. We explain this synergistic effect by the simultaneous variation in CO2 binding energy and decomposition barrier as the Fe/Co ratio in the nanoalloy changes. With increasing Fe content, increased activation temperatures for the formation of CH4 (from 440 K to 560 K) and C2-C5 hydrocarbons (from 460 K to 560 K) are observed.

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Structural and magnetic properties of Co Fe3−O4 versus Co/Fe molar ratio

Cited by 51 publications

References 30 publications

Efficient spinel iron-cobalt oxide/nitrogen-doped ordered mesoporous carbon catalyst for rechargeable zinc-air batteries

Efficient spinel iron-cobalt oxide/nitrogen-doped ordered mesoporous carbon catalyst for rechargeable zinc-air batteries

Crystal structures and magnetic properties of polyethylene glycol/polyacrylamide encapsulated CoCuFe4O8 ferrite nanoparticles

CO2 Hydrogenation over Unsupported Fe-Co Nanoalloy Catalysts

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