Graphene-like porous activated carbon sheets derived from biomass wood for high-performance organic supercapacitors and hydrogen (H2) storage

Graphene-like porous activated carbon (PAC) sheets were synthesized from biomass using NaOH porogen at various activation temperatures (600−900 °C), and their potential for high-energy supercapacitors and hydrogen (H2) storage applications is successfully demonstrated. Quenched Solid Density Functional Theory analysis was conducted to understand the evolution of porosity in PACs as a function of the activation temperature and its impact on the electrochemical performance of electrodes. The PAC synthesized at 800 °C (PAC-800) exhibited a high specific capacitance of 459.4 F g−1 at 0.5 A g−1 , owing to the synergistic effects of enhanced graphitization, large specific surface area (1581 m2 g−1 ), and coexisting micro- and mesopores. Furthermore, PACs with superior electrochemical properties have been successfully integrated into coin-type supercapacitors with organic electrolytes. The fabricated PAC-800 symmetrical supercapacitor coin cell in a 1 M LiPF6 electrolyte delivered a specific energy of 46.5 W h kg−1 with a potential window of 2.5 V. In addition, using 1 M NaPF6 electrolyte, a maximum power density of 223.3 kW kg−1 and an energy density of 65.7 Wh kg−1 were demonstrated due to the extended voltage window of 3.5 V with a cyclic stability of 85 % after 10,000 cycles. The PAC materials show promising potential for H2 storage, with measured capacities in the range of 0.7−1.5 wt.% at 77 K and 1 bar, indicating their applicability in broader energy storage applications.