A novel approach to prepare poly(3,4-ethylenedioxythiophene) nanoribbons between V₂O₅ layers by microwave irradiation

Abstract

Rapid synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) nanoribbons interleaved between the layers of crystalline V₂O₅ is achieved for the first time under microwave irradiation via the redox intercalative polymerization reaction of 3,4-ethylenedioxythiophene (EDOT) monomer and crystalline V₂O₅ at different time intervals. Compared with the conventional 12 h of refluxing for intercalative polymerization, the microwave-assisted redox polymerization process proceedes rapidly, enabling the expansion of the interlayer spacing of crystalline V₂O₅ from 0.43 to 1.41 nm within 8 min. The characterization of this material using powder XRD, XPS, EPR, SEM, and HRTEM analysis supports the intercalation of the polymer between V₂O₅ layers, leading to enhanced bidimensionality. XPS analysis clearly shows the presence of mixed-valent V⁴⁺/V⁵⁺ in the V₂O₅ framework after the redox intercalative polymerization, which also confirms charge transfer from the polymer to the V₂O₅ framework. EPR study also reveals redox processes during EDOT insertion and polymerization between the V₂O₅ layers. After PEDOT insertion into V₂O₅, the EPR signal from VO²⁺ is more pronounced as the intensity of the signal increases as compared to that of pristine V₂O₅. This nanocomposite when coupled with a large-area Li foil electrode in 1 M LiClO₄ in a mixture of ethylene and dimethyl carbonate (1:1 by volume) gives a discharge capacity of ~350 mA h g⁻¹, which is significantly higher than that of pristine V₂O₅.