Micelle anchored in situ synthesis of V2O3 nanoflakes@C composites for supercapacitors

Abstract

A micelle-anchoring method has been developed for the in situ synthesis of V₂O₃ nanoflakes@C core–shell composites as the electrode materials in supercapacitors. Hexadecyltrimethylammonium bromide (CTAB) micelles assembled to solubilize activated carbon and anchor vanadate ions of the precursor, NH₄VO₃, onto the carbon surface. During drying and calcination, CTAB and NH₄VO₃ decompose to produce V₂O₅, which is carbon-thermally reduced to V₂O₃in situ. In the as-obtained composites, monodisperse V₂O₃ nanoflakes stand edge-on the carbon surface, forming a carbon core with a shell layer of edge-on standing V₂O₃ nanoflakes. Because of the increased electric conductivity and high specific surface area, V₂O₃ nanoflakes@C composites exhibit a specific capacitance of 205 F g⁻¹ at 0.05 A g⁻¹ over a potential range of −0.4 to 0.6 V, which surpasses those of their individual counterparts (67 F g⁻¹ and 159 F g⁻¹ at 0.05 A g⁻¹ for activated carbon and bulk V₂O₃, respectively). The composites also showed good cycling stability due to structure support of the inner carbon cores. The proposed method provides a novel strategy to synthesize composites of transition-metal oxides with improved electrochemical performance for applications in supercapacitors.