Vanadium oxide nanorings: Facile synthesis, formation mechanism and electrochemical properties

This paper describes the hydrothermal synthesis of vanadium oxide nanorings and nanobelts from aqueous precursors without using any template. These nanorings are formed via the acidification of sodium metavanadate solution. A simple ion intercalation/de-intercalation process occurs under mild hydrothermal conditions leading to the self-rolling of exfoliated vanadium oxide nanobelts. The structure and morphology of the products are characterized by XRD, SEM, TEM and charge-discharge measurement. XRD pattern reveals that the products consist of V2O5 nanorings and Na0.3V2O5 nanobelts evidenced by SEAD pattern and EDS. Highly magnified TEM images exhibit nanorings made of nanoribbons of width about 300 nm and thickness of about 60 nm. Electrochemical analyses revealed that the V2O5 nanorings/nanobelts delivers an initial lithium-ion intercalation capacity of 280 mAh g−1 and reaches a stabilized capacity of 200 mAh g−1 at a current density of 100 mA g−1.