A beltlike V2O3@C core–shell-structured composite was successfully synthesized by thermal treatment with the precursor V3O7·H2O@C composite under an inert atmosphere. The phase, composition, structure, and morphology of the as-obtained samples were confirmed by XRD, elemental analysis, FTIR, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), IR Raman, SEM, and TEM measurements. The process of the formation of V2O3@C is briefly discussed. The carbon coated onto the surface of V2O3 is disordered, and V2O3 keeps the original morphology of V3O7·H2O. V2O3@C has an average length that ranges from 0.4 to 5.2 μm, a width of about 80–170 nm, and an average thickness of the shells of about 15.6 nm. The possible formation mechanism of V2O3@C is proposed as follows: the reaction undergoes a solid-state reaction by the interface reaction between V3O7 cores and carbon shells. It was found that the V2O3@C composite possesses the same phase-transition properties as V2O3, which could expand the possible applications of materials related to V2O3 in the future. Furthermore, a V2O3 sphere, a V2O3 nanobelt, and the beltlike V2O3@C composite were explored as cathode materials for application in lithium-ion batteries. The beltlike V2O3@C composite electrode exhibited the best electrochemical properties among them, thereby achieving our aim of improving the electrochemical properties of V2O3.

Beltlike V2O3@C Core–Shell-Structured Composite: Design, Preparation, Characterization, Phase Transition, and Improvement of Electrochemical Properties of V2O3

Highly ordered lamellar V2O3-based hybrid nanorods towards superior aqueous lithium-ion battery performance

The vanadium(III) cation structure in mixed acid based electrolyte solution from vanadium redox flow batteries is studied by 17O and 35/37Cl nuclear magnetic resonance (NMR) spectroscopy, electronic spectroscopy and density functional theory (DFT) based computational modelling. Both computational and experimental results reveal that the V(III) species can complex with counter anions (sulfate/chlorine) depending on the composition of its solvation sphere. By analyzing the powder precipitate it was found that the formation of sulfate complexed V(III) species is the crucial process in the precipitation reaction. The precipitation occurs through nucleation of neutral species formed through deprotonation and ion-pair formation process. However, the powder precipitate shows a multiphase nature which warrants multiple reaction pathways for precipitation reaction.

Structure and stability of hexa-aqua V(III) cations in vanadium redox flow battery electrolytes

Synthesis and characterization of belt-like VO2(B)@carbon and V2O3@carbon core–shell structured composites

In this work, VO2 nanorods have been initially generated as reactive nanoscale precursors to their subsequent conversion to large quantities of highly crystalline V2O3 with no detectable impurities. Structural changes in VO2, associated with the metallic-to-insulating transition from the monoclinic form to the rutile form, have been investigated and confirmed using X-ray diffraction and synchrotron data, showing that the structural transition is reversible and occurs at around 63 °C. When this VO2 one-dimensional sample was subsequently heated to 800 °C in a reducing atmosphere, it was successfully transformed into V2O3 with effective retention of its nanorod morphology. We have also collected magnetic and transport data on these systems that are comparable to bulk behavior and consistent with trends observed in previous experiments.

Synthesis and characterization of V2O3 nanorods.

V 2 O 3 with spherical particles was hydrothermally synthesized (240 °C, 48 h, autogenous pressure) as a single-phase material from a mixture of V 2 O 5 , 1,6-diaminohexane and H 2 O in the mol ratio 1:1:269. It was characterized by scanning electronic microscopy, X-ray powder diffraction, thermal analysis and electron paramagnetic resonance.

N. Gharbi

Papers

Hydrothermal synthesis and characterization of V2O3