N-doped/oxygen-deficient Fe2O3−x @PEDOT cruciform nanosheet arrays: Boosting the performance of all-solid-state flexible supercapacitors

Abstract

As an ideal Faradaic anode material, Fe2O3 is expected to achieve high electrochemical performance in supercapacitors. However, the application of Fe2O3 in supercapacitors is limited by poor conductivity. In this study, first, we synthesized Fe2O3@Poly(3,4-ethylenedioxythiophene) (Fe2O3@PEDOT) composite cruciform nanosheet arrays via a one-step Fe3+-induced growth strategy. Fe2O3 nanoparticles were uniformly confined in ultrathin PEDOT sheets to enhance the dispersibility and conductivity of Fe2O3. Then, oxygen vacancies and nitrogen doping were introduced in Fe2O3 nanoparticles by plasma treatment (N-Fe2O3−x@PEDOT), which further enhanced the conductivity of Fe2O3 and increased the number of active sites. The engineered N-Fe2O3−x@PEDOT composites exhibited a high area capacitance of approximately 751 mF cm−2 at a current density of 1 mA cm−2 and approximately 103 mF cm−2 at 5 mV s−1 for a corresponding symmetric solid-state flexible supercapacitor with a capacitance retention of ∼60% after 5000 cycles.