Phase transformation and electrochemical charge storage properties of vanadium oxide/carbon composite electrodes synthesized via integration with dopamine

Chemically preintercalated dopamine (DOPA) molecules were used as both a reducing agent and a carbon precursor to prepare δ-V₂O₅·nH₂O/C, H₂V₃O₈/C, VO₂(B)/C, and V₂O₃/C nanocomposites via hydrothermal treatment or hydrothermal treatment followed by annealing under Ar flow. We found that the phase composition and morphology of the produced composites are influenced by the DOPA:V₂O₅ ratio used to synthesize (DOPA)_xV₂O₅ precursors through DOPA diffusion into the interlayer region of the δ-V₂O₅·nH₂O framework. The increase of DOPA concentration in the reaction mixture led to a more pronounced reduction of vanadium and a higher fraction of carbon in the composites’ structure, as evidenced by X-ray photoelectron spectroscopy and Raman spectroscopy measurements. The electrochemical charge storage properties of the synthesized nanocomposites were evaluated in Li-ion cells with nonaqueous electrolytes. δ-V₂O₅·nH₂O/C, H₂V₃O₈/C, VO₂(B)/C, and V₂O₃/C electrodes delivered high initial capacities of 214, 252, 279, and 637 mAh g^–1, respectively. The insights provided by this investigation open up the possibility of creating new nanocomposite oxide/carbon electrodes for a variety of applications, such as energy storage, sensing, and electrochromic devices.