Synergistic Effects of Fe2O3 Nanotube/Polyaniline Composites for an Electrochemical Supercapacitor with Enhanced Capacitance

α-Fe2O3, which is an attractive material for supercapacitor electrodes, has been studied to address the issue of low capacitance through structural development and complexation to maximize the use of surface pseudocapacitance. In this study, the limited performance of α-Fe2O3 was greatly improved by optimizing the nanotube structure of α-Fe2O3 and its combination with polyaniline (PANI). α-Fe2O3 nanotubes (α-NT) were fabricated in a form in which the thickness and inner diameter of the tube were controlled by Fe(CO)5 vapor deposition using anodized aluminum oxide as a template. PANI was combined with the prepared α-NT in two forms: PANI@α-NT-a enclosed inside and outside with PANI and PANI@α-NT-b containing PANI only on the inside. In contrast to α-NT, which showed a very low specific capacitance, these two composites showed significantly improved capacitances of 185 Fg−1 for PANI@α-NT-a and 62 Fg−1 for PANI@α-NT-b. In the electrochemical impedance spectroscopy analysis, it was observed that the resistance of charge transfer was minimized in PANI@α-NT-a, and the pseudocapacitance on the entire surface of the α-Fe2O3 nanotubes was utilized with high efficiency through binding and conductivity improvements by PANI. PANI@α-NT-a exhibited a capacitance retention of 36% even when the current density was increased 10-fold, and showed excellent stability of 90.1% over 3000 charge–discharge cycles. This approach of incorporating conducting polymers through well-controlled nanostructures suggests a solution to overcome the limitations of α-Fe2O3 electrode materials and improve performance.

Polypyrrole-coated Fe2O3 nanotubes constructed from nanoneedles as high-performance anodes for aqueous asymmetric supercapacitors

Polypyrrole-coated Fe2O3 nanotubes constructed from nanoneedles have been fabricated on nickel foam with excellent performance as anodes for supercapacitors.

In Situ Vapor Polymerization of Poly(3,4-ethylenedioxythiophene) Coated SnO2-Fe2O3 Continuous Electrospun Nanotubes for Rapid Detection of Iodide Ions

In this work poly(3,4-ethylenedioxythiophene) (PEDOT) coated SnO2-Fe2O3 continuous nanotubes with a uniform core–shell structure have been demonstrated for rapid sensitive detection of iodide ions. The SnO2-Fe2O3 nanotubes were firstly fabricated via an electrospinning technique and following calcination process. An in situ polymerization approach was then performed to coat a uniform PEDOT shell on the surface of as-prepared SnO2-Fe2O3 nanotubes by vapor phase polymerization, using Fe2O3 on the surface of nanotubes as an oxidant in an acidic condition. The resultant PEDOT@SnO2-Fe2O3 core-shell nanotubes exhibit a fast response time (~4 s) toward iodide ion detection and a linear current response ranging from 10 to 100 μM, with a detection limit of 1.5 μM and sensitivity of 70 μA/mM/cm2. The facile fabrication process and high sensing performance of this study can promote a wide range of potential applications in human health monitoring and biosensing systems.