Characterizations and EDLC Performances of Large-Scale Synthesized Zeolite-Templated Carbons

We have recently reported the large-scale synthesis of zeolite-templated carbon (ZTC) using biomass resources (ACS Sustainable Chem. Eng. 10 (2022) 10827−10838, Carbon Trends 9 (2022) 100228). In this method, undried NaY zeolite was mixed with a biomass resource such as sugar or starch as a carbon source. The mixture was subjected to chemical vapor deposition using propylene as an additional carbon source and subsequent heat treatment for graphitization, followed by zeolite removal with HF. The resulting ZTCs exhibited high structural regularity and large specific surface areas of 3750–3820 m2 g−1. This simple method eliminated the use of organic solvents and minimally reduced the amount of the carbon sources. In this work, we analyzed these ZTCs using temperature programmed desorption (TPD) to quantitatively and qualitatively determine oxygen-containing functional groups, as well as other structural characterizations. Finally, their electric double-layer capacitor performances were evaluated using an organic electrolyte, 1 M Et4NBF4/propylene carbonate. The TPD analysis revealed that sucrose- and xylose-derived ZTCs had a large amount of phenol group in comparison to the glucose- and starch-derived ZTCs. Due to the initial deprotonation of phenol group and reversible redox reaction of the resulting redox-active quinone group, sucrose- and xylose-derived ZTCs showed higher capacitance than the rest through large pseudocapacitance with maintaining high capacitance retentions of 89–92% at 2 A g−1 by comparing the capacitances at 0.05 A g−1. Although their area-normalized capacitances of 0.036–0.039 F m−2 were lower than those of activated carbon because of the low electrical conductivity of the ZTCs, the capacitance of these ZTCs can be further enhanced by electrochemical oxidation.