Designing 3D Ternary Hybrid Composites Composed of Graphene, Biochar and Manganese Dioxide as High-Performance Supercapacitor Electrodes

Biochar derived from waste biomass has proven to be an encouraging novel electrode material in supercapacitors. In this work, luffa sponge-derived activated carbon with a special structure is produced through carbonization and KOH activation. The reduced graphene oxide (rGO) and manganese dioxide (MnO2) are in-situ synthesized on luffa-activated carbon (LAC) to improve the supercapacitive behavior. The structure and morphology of LAC, LAC-rGO and LAC-rGO-MnO2 are characterized by the employment of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), BET analysis, Raman spectroscopy and scanning electron microscopy (SEM). The electrochemical performance of electrodes is performed in two and three-electrode systems. In the asymmetrical two-electrode system, the LAC-rGO-MnO2//Co3O4-rGO device shows high specific capacitance (SC), high-rate capability and excellent cycle reversibly in a wide potential window of 0-1.8 V. The maximum specific capacitance (SC) of the asymmetric device is 586 F g(-1) at a scan rate of 2 mV s(-1). More importantly, the LAC-rGO-MnO2//Co3O4-rGO device exhibits a specific energy of 31.4 W h kg(-1) at a specific power of 400 W kg(-1). Overall, the synergistic effect between the ternary structures of microporous LAC, rGO sheets and MnO2 nanoparticles leads to the introduction of high-performance hierarchical supercapacitor electrodes.

Automated summary

This study produces special-structured activated carbon derived from luffa sponge through carbonization and KOH activation, which proves to be an encouraging novel electrode material in supercapacitors. Reduced graphene oxide (rGO) and manganese dioxide (MnO2) are synthesized on luffa-activated carbon (LAC) to enhance its supercapacitive behavior. The combination of microporous LAC, rGO sheets and MnO2 nanoparticles results in high-performance hierarchical supercapacitor electrodes.