Surface characteristics and electrochemical properties of activated carbon obtained from different parts of Pinus pinaster
By Yumak, Tuğrul
Published in Colloids and Surfaces A: Physicochemical and Engineering Aspects
2021
Abstract
Different parts (needle and cone) of the same biomass (pine, Pinus pinaster) were used as carbon source for activated carbon production. Biomass-derived activated carbons (ACs) were produced by the chemical activation of pyrolytic char. Dependence of the surface characteristics to the biomass type and activation agent were discussed by N2 Physisorption, Raman, and X-ray photoelectron spectroscopy (XPS) techniques. Pine-cone-derived ACs exhibit higher BET surface area and mesopore volume to micropore volume ratio compared to needle-derived ACs. Regardless of the biomass type, higher BET surface area and Vmes/Vmic ratio were obtained by KOH activation. XPS results proved that the KOH dominantly reacts with the aliphatic groups while H3PO4 reacts with aromatic groups during the activation. Hence, KOH activation led to the higher relative amounts of surface aromatic groups which will contribute to the total specific capacitance by creating pseudocapacitance. The electrochemical performance of the synthesized ACs was determined in packaged supercapacitors in CR2032 casings. Galvanostatic charge-discharge and self-discharge tests proved that all packaged supercapacitors displayed a repeatable cycle behavior and were highly stable. Cone-derived AC-based supercapacitors displayed higher specific capacitance than those of needle-derived ACs at all current densities (0.25–1 A/g). However, higher ESR values were observed for cone-derived AC based electrodes. The cone-derived AC (by KOH activation) based supercapacitor displayed 99% capacitance retention over 5000 cycles at 500 mA/g current density. It is found that the biomass type primarily affects the surface and electrochemical properties of ACs.