Structural changes and electrochemical properties of mesoporous activated carbon derived from Eucommia ulmoides wood tar by KOH activation for supercapacitor applications

In this study, mesoporous activated carbon (AC) was synthesized by thermochemical activation of Eucommia ulmoides Oliver (EUO) wood tar by using KOH as the activator. The pore structure, surface characteristics, graphitization degree and electrochemical properties of ACs synthesized by one-step and two-step activation were systematically investigated. The results showed that the two-step activation could effectively improve the relevant properties of AC as compared to those from the one-step activation. The maximum specific surface area (SSA) and pore volume of AR3–1 (1:3 mass ratio of EUO wood tar to activator at one-step activation process) could be increased than AR3–2 (1:3 mass ratio of carbonized product to activator at two-step activation process) by 26.08% and 20.27%, respectively. Additionally, the mesoporous ratio of AR3–2 can reach 71%, indicating a well-developed mesoporous structure. Meanwhile, the highest SSA of AR5–2 (1:5 mass ratio of carbonized product to activator at two-step activation process) synthesized by two-step activation can rise to 3354.8 m2/g, and the pore volume can reach 1.78 m3/g. Besides, the specific capacitance of AR3–2 reached 510.54 F/g at a current density of 0.2 A/g in 1 M KOH aqueous electrolyte in the three-electrode system, possessing better electrochemical stability. Overall, as a precursor of mesoporous activated carbon, the AC synthesized from EUO wood tar exhibits excellent structural and electrochemical performance. This study has a guiding significance for the synthesis of high-performance mesoporous carbon from biomass tar.