Fabrication of Highly Conductive Porous FeO@RGO/PEDOT:PSS Composite Films via Acid Post-Treatment and Their Applications as Electrochemical Supercapacitor and Thermoelectric Material.

As a remarkable multifunctional material, ferroferric oxide (FeO) exhibits considerable potential for applications in many fields, such as energy storage and conversion technologies. However, the poor electronic and ionic conductivities of classical FeO restricts its application. To address this challenge, FeO nanoparticles are combined with graphene oxide (GO) via a typical hydrothermal method, followed by a conductive wrapping using poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic sulfonate) (PEDOT:PSS) for the fabrication of composite films. Upon acid treatment, a highly conductive porous FeO@RGO/PEDOT:PSS hybrid is successfully constructed, and each component exerts its action that effectively facilitates the electron transfer and subsequent performance improvement. Specifically, the FeO@RGO/PEDOT:PSS porous film achieves a high specific capacitance of 244.7 F g at a current of 1 A g. Furthermore, due to the facial fabrication of the highly conductive networks, the free-standing film exhibits potential advantages in flexible thermoelectric (TE) materials. Notably, such a hybrid film shows a high electric conductivity (σ) of 507.56 S cm, a three times greater value than the FeO@RGO component, and achieves an optimized Seebeck coefficient (S) of 13.29 μV K at room temperature. This work provides a novel route for the synthesis of FeO@RGO/PEDOT:PSS multifunctional films that possess promising applications in energy storage and conversion.