Facile Preparation of Oxygen Vacancy WO<sub>3-X</sub>@TiO<sub>2-X</sub>/Poly(indole-6-carboxylic acid) Ternary Composites with Enhanced Energy Storage Capacity and Their Supercapacitor Application
Qingfu Guo, Qing Li, Lu Zheng, Xuejiao Xu, Guangming Nie
Abstract
WO3-X@TiO2-X nanocomposites with oxygen vacancies are successfully prepared by hydrothermal synthesis, which have the best electrochemical properties at a Ti/W ratio of 0.6. Then WO3-X@TiO2-X/poly(indole-6-carboxylic acid) (WO3-X@TiO2-X/P6ICA) nanocomposites are obtained by electrochemical polymerization of P6ICA on the surface of WO3-X@TiO2-X. The electrochemical and supercapacitive properties of WO3-X@TiO2-X/P6ICA nanocomposites are studied. The analysis shows that the presence of oxygen vacancy in WO3-X@TiO2-X greatly enhances the charge transfer capacity and shortens the charge and discharge time of the material. And P6ICA enhances not only the conductivity of the novel compound but also its energy storage capacity. Due to the synergistic effect between WO3-X@TiO2-X and P6ICA, the WO3-X@TiO2-X/P6ICA nanocomposite shows good electrochemical property, supercapacitive properties, and enhanced charge transfer rate. The maximum specific capacitance value of the prepared WO3-X@TiO2-X/P6ICA nanocomposites can reach 60.8 mF cm–2 (or 878.6 F g–1). An asymmetric supercapacitor device based on WO3-X@TiO2-X/P6ICA nanocomposites and poly(3,4-ethylenedioxythiophene) (PEDOT) is successfully constructed, which also shows a high energy storage level of 22.0 mF cm–2 (or 317.9 F g–1). The supercapacitors with good cycling stability can continuously light up a LED for 90 s. Based on these results, the prepared WO3-X@TiO2-X/P6ICA ternary composites may have potential applications in supercapacitors.