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