Polyhedral Magnetite Nanocrystals with Multiple Facets: Facile Synthesis, Structural Modelling, Magnetic Properties and Application for High Capacity Lithium Storage

Su, Dawei; Horvat, J.; Munroe, Paul; Ahn, Hyo‐Jun; Ranjbartoreh, Ali Reza; Wang, Guoxiu

doi:10.1002/chem.201101939

Cited by 26 publications

(23 citation statements)

References 74 publications

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“…213) maghemite‐rich phase ( a =8.352 Å) and the CP NPs were characterized as Fd 3 m (no. 227) magnetite‐rich phase ( a =8.396 Å) 30. As the difference between maghemite and magnetite is subtle in XRD, no conclusions about the exact composition can be drawn and this is in accordance with a previous comparison of the two systems 31.…”

Section: Resultssupporting

confidence: 72%

Experimental and First‐Principles Characterization of Functionalized Magnetic Nanoparticles

et al. 2013

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Magnetic iron oxide nanoparticles synthesized by coprecipitation and thermal decomposition yield largely monodisperse size distributions. The diameters of the coprecipitated particles measured by X-ray diffraction and transmission electron microscopy are between approximately 9 and 15 nm, whereas the diameters of thermally decomposed particles are in the range of 8 to 10 nm. Coprecipitated particles are indexed as magnetite-rich and thermally decomposed particles as maghemite-rich; however, both methods produce a mixture of magnetite and maghemite. Fourier transform IR spectra reveal that the nanoparticles are coated with at least two layers of oleic acid (OA) surfactant. The inner layer is postulated to be chemically adsorbed on the nanoparticle surface whereas the rest of the OA is physically adsorbed, as indicated by carboxyl O-H stretching modes above 3400 cm(-1). Differential thermal analysis (DTA) results indicate a double-stepped weight loss process, the lower-temperature step of which is assigned to condensation due to physically adsorbed or low-energy bonded OA moieties. Density functional calculations of Fe-O clusters, the inverse spinel cell, and isolated OA, as well as OA in bidentate linkage with ferrous and ferric atoms, suggest that the higher-temperature DTA stage could be further broken down into two regions: one in which condensation is due ferrous/ferrous- and/or ferrous/ferric-OA and the other due to condensation from ferrous/ferric- and ferric/ferric-OA complexes. The latter appear to form bonds with the OA carbonyl group of energy up to fivefold that of the bond formed by the ferrous/ferrous pairs. Molecular orbital populations indicate that such increased stability of the ferric/ferric pair is due to the contribution of the low-lying Fe(3+) t(2g) states into four bonding orbitals between -0.623 and -0.410 a.u.

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Section: Resultssupporting

confidence: 72%

Experimental and First‐Principles Characterization of Functionalized Magnetic Nanoparticles

et al. 2013

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“…Transition metal oxides have been extensively investigated as high capacity anodes for Li-ion batteries. [28][29][30][31][32] Therefore, it could be possible to apply transition metal oxides for Na ion storage in Na-ion batteries. However, none of them demonstrated comparable performances for Na-ion batteries.…”

Section: Introductionmentioning

confidence: 99%

Octahedral tin dioxide nanocrystals as high capacity anode materials for Na-ion batteries

Wang

Ahn

et al. 2013

Phys. Chem. Chem. Phys.

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118

121

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Single crystalline SnO2 nanocrystals (~60 nm in size) with a uniform octahedral shape were synthesised using a hydrothermal method. Their phase and morphology were characterized by XRD and FESEM observation. TEM and HRTEM analyses identified that SnO2 octahedral nanocrystals grow along the [001] direction, consisting of dominantly exposed {221} high energy facets. When applied as anode materials for Na-ion batteries, SnO2 nanocrystals exhibited high reversible sodium storage capacity and excellent cyclability (432 mA h g(-1) after 100 cycles). In particular, SnO2 nanocrystals also demonstrated a good high rate performance. Ex situ TEM analysis revealed the reaction mechanism of SnO2 nanocrystals for reversible Na ion storage. It was found that Na ions first insert into SnO2 crystals at the high voltage plateau (from 3 V to ~0.8 V), and that the exposed (1 × 1) tunnel-structure could facilitate the initial insertion of Na ions. Subsequently, Na ions react with SnO2 to form NaxSn alloys and Na2O in the low voltage range (from ~0.8 V to 0.01 V). The superior cyclability of SnO2 nanocrystals could be mainly ascribed to the reversible Na-Sn alloying and de-alloying reactions. Furthermore, the reduced Na2O "matrix" may help retard the aggregation of tin nanocrystals, leading to an enhanced electrochemical performance.

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“…All impedances were measured at 3 V from 0.01 Hz to 100 kHz. The Nyquist plots consist of a semicircle in high frequency region which can be ascribed to the charge transfer process at the interfaces between electrolyte and electrode [53], and a straight line in the low frequency region. Prior to the first cycle, the electrode shows a smaller diameter semicircle relative to after 15 cycles, indicating that the charge transfer resistance increases with cycling, perhaps due to SEI formation.…”

Section: Resultsmentioning

confidence: 99%

Three-dimensionally scaffolded Co3O4 nanosheet anodes with high rate performance

Liu

Kelly

Epstein

et al. 2015

Journal of Power Sources

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Advances in secondary batteries are required for realization of many technologies. In particular, there remains a need for stable higher energy batteries. Here we suggest a new anode concept consisting of an ultrathin Co 3 O 4 nanosheet-coated Ni inverse opal which provides high charge-discharge rate performance using a material system with potential for high energy densities. Via a hydrothermal process, about 4 nm thick Co 3 O 4 nanosheets were grown throughout a three-dimensional Ni scaffold. This architecture provides efficient pathways for both lithium and electron transfer, enabling high charge-discharge rate performance. The scaffold also accommodates volume changes during cycling, which serves to reduce capacity fade. Because the scaffold has a low electrical resistance, and is three-dimensionally porous, it enables most of the electrochemically active nanomaterials to take part in lithiation-delithiation reactions, resulting in a near-theoretical capacity. On a Co 3 O 4 basis, the Ni@Co 3 O 4 electrode possesses a capacity of about 726 mAh g −1 at a current density of 500 mA g −1 after 50 cycles, which is about twice the theoretical capacity of graphite. The capacity is 487 mAh g −1 , even at a current density of 1786 mA g −1 .

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Polyhedral Magnetite Nanocrystals with Multiple Facets: Facile Synthesis, Structural Modelling, Magnetic Properties and Application for High Capacity Lithium Storage

Cited by 26 publications

References 74 publications

Experimental and First‐Principles Characterization of Functionalized Magnetic Nanoparticles

Experimental and First‐Principles Characterization of Functionalized Magnetic Nanoparticles

Octahedral tin dioxide nanocrystals as high capacity anode materials for Na-ion batteries

Three-dimensionally scaffolded Co3O4 nanosheet anodes with high rate performance

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