Nanoarchitectonics of hierarchical porous carbon based on carbonization of heavy fraction of bio-oil and its supercapacitor performance

As a by-product of biomass pyrolysis process, the heavy fraction in bio-oil is characterized by high carbon content, easy polymerization and carbonization and abundant oxygen-containing functional groups, making it a suitable precursor for the synthesis of porous carbon. In this study, nanoarchitectonics of hierarchical porous carbon were prepared from the heavy fraction in bio-oil produced by pyrolysis of rice husk biomass with calcium citrate (C12H10Ca3O14) as a template agent and potassium oxalate (K2C2O4) as an activator. The roles of templating agents and activators in the carbonization polymerization of heavy oil were discussed by TG, BET, SEM, TEM, FTIR, XRD, Raman, XPS and other characterization analyses. C12H10Ca3O14 could promote the formation of mesopores, while the activation etching effect of K2C2O4 was the main source of micropores. The porous carbon effectively inherited the rich oxygen-containing functional groups in bio-oil and had a nanosheet structure with a specific surface area of 1905.3 m2/g. Supercapacitor performance of porous carbon was analyzed through electrochemical performance tests. The specific capacitance reached 233.4 F/g at 0.5 A/g and remained 205.0 F/g at 10 A/g. The attenuation rate was only 12.2 % when the current density increased by 50 times. After 10,000 cycles, the specific capacitance retention of the sample reached 92.3 %. The energy density reached 7.2 Wh/kg at a power density of 239.3 W/kg.