Free standing Co₃O₄ decorated carbon foam derived from phenolic resin for high-performance supercapacitor

Herein, a novel method to fabricate a cobalt oxide (Co₃O₄) nanostructure decorated with lightweight free-standing carbon foam (CF) has been reported. Firstly, the free standing CF was fabricated via a polyurethane (PU) foam replica method using phenolic resin, followed by oxidation stabilization and finally carbonization at 1000°C in an inert atmosphere. Secondly, different contents of Co₃O₄ nanoparticles (NPs) were decorated on free-standing CF using the in-situ hydrothermal method. The developed foams have been extensively studied for various electrochemical characteristics including cyclic voltammetry (CV), capacitance, and electrochemical impedance spectroscopy (EIS) in 1 M KOH solution using a three-electrode system. The structural and morphological investigation of foams were examined by XRD, Raman, and SEM. It is observed that Co₃O₄ NPs are uniformly decorated on CF and the electrochemical performance of CF is improved synergistically. The asymmetrical two-cell supercapacitor composed of CF-10Co₃O₄ positive electrode and CF negative electrode exhibited a specific capacitance of 164 F g^-1 at a current density of 0.5 A g^-1. The device (CF-10Co₃O₄//CF) can deliver a high energy density of 44 Wh kg^-1 at the power density of 350 W kg^-1. The high specific capacitance and large energy density demonstrate the potential application of carbon-Co₃O₄ decorated foams in compact and lightweight supercapacitor. (author)