Facile one-step synthesis of 0D to 3D VO_x nanostructures for energy storage

Vanadium oxides (VO_x) and their related compounds have been received extensive attentions because of their special chemical and physical properties, which make them have a wide range of practical applications. VO_x can offer high pseudocapacitance for energy storage due to its high electrochemical activity. Herein, 0D (nanoparticles), 1D (nanowires), 2D (nanosheets) & 3D (nanodonuts) VO_x were successfully synthesized with assistance of glucose by a facile one-step hydrothermal method. The relationship between the structure and the electrochemical properties of VO_x was investigated in detail. Among all the morphologies, the donut-like VO_x displays the best pseudocapacitive performance under our reported conditions, with a specific capacitance as high as 225.8 F g⁻¹ at a scan rate of 2 mV s⁻¹. The synergy effect between multiple vanadium oxidation states (mixed-valence) and the donut-like geometry contributes to electrochemical properties. That is, the mixed-valence offers theoretical specific capacitance and the unique donut-like structure provides a more active surface and supported high-speed ionic and electronic transmission channels. The good electrochemical performance of the 0-3D VO_x nanostructures indicates their high potential as electrode materials for supercapacitors.