A new approach to in-situ Co3O4 nanostructure decorated free-standing carbon foam derived from phenolic resin for high-performance supercapacitor

Herein, a novel method to fabricate a cobalt oxide (Co3O4) nanostructure decorated with lightweight freestanding carbon foam (CF) has been reported. Primarily, the freestanding CF was fabricated via a polyurethane (PU) foam replica method using phenolic resin, followed by oxidation stabilization and finally carbonization at 1000 oC in an inert atmosphere. After that 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 was 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. Consequently, the specific capacitance (302 F g-1 at mV s-1) was greatly enhanced when the CF was decorated with 10 % Co3O4 NPs. Moreover, an 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 carbonCo3O4 decorated foams in compact and lightweight supercapacitors.