Metal Oxide-Assisted PEDOT Nanostructures via Hydrolysis-Assisted Vapor-Phase Polymerization for Energy Storage

The diversity of nanostructures obtained from organic polymerization is limited when compared to the huge amount of documented inorganic nanostructures. In this paper, we elucidate a synergistic mechanism between in situ inorganic salt hydrolysis and vapor-phase polymerization for the metal oxide-poly(3,4-ethylenedioxythiophene) (PEDOT) hybrid nanostructure growth. The steady state polymer growth and kinetically controlled hydrolysis enables homogeneous deposition of high-aspect-ratio crystal phases such as β-FeOOH, TeO2, and SnO2 coated by a conducting polymer. By controlling the hydrolysis kinetics, the hybrid material is synthesized in one step with morphologies controlled from 1D nanofibers to 2D nanoflowers and nanostructures from monolithic to core–shell. This fundamental understanding of the connection between hydrolysis and polymerization allows the future development of nanostructured inorganic, polymeric, and inorganic–organic hybrid materials. Enabled by this study, electrodes for energy storage are fabricated with different PEDOT morphologies, and their structure–property relationships are discussed. The 1D fibrillar structure shows a higher capacitance of 185 F/g at 25 mV/s compared to 2D nanoflowers because this morphology enhances electrolyte diffusion kinetics that facilitate PEDOT doping and dedoping, leading to a lower internal resistance.