Facile synthesis of high-surface-area activated carbon from coal for supercapacitors and high CO2 sorption†
Abstract
Carbon materials have attracted much attention in many applications. Herein, high performance activated carbons (ACs) were synthesized from cheap coal raw material via a facile strategy by KOH activation. AC4T800t2 exhibited the higher BET surface area (2457 m2 g−1) and larger total pore volume (1.448 cm3 g−1) among the as-synthesized ACs samples. The optimized material (AC4T800t2) displayed a specific capacitance as high as 384 F g−1 at a scan rate of 5 mV s−1 in 6 M KOH. The capacitance remained still at 279 F g−1, even at a high scan rate of 200 mV s−1, showing good rate performance. AC4T800t2 also showed excellent cycle performance (95% retention capacity after 5000 cycles) at a current density of 5 A g−1. Furthermore, these ACs samples for CO2 sorption were also investigated using a pressure swing adsorption (PSA) process. The CO2 sorption behaviors of these samples were tested at 298.15 K in a pressure range of 0–1 MPa by the volumetric method. The Langmuir model provided good agreement with the experimental data (correlation coefficient above 0.99). The optimized material (AC4T800t2) showed a high CO2 sorption capacity of 169.44 mL g−1 (7.56 mmol g−1) at 1 MPa, also a high CO2 saturated uptake of 20.81 mmol g−1 (91.56 wt%). Better CO2 uptake is dependent on a larger micropore volume and higher specific surface area. In brief, the high performance AC samples have been synthesized for supercapacitors and CO2 sorption.