Scalable synthesis of biomass-derived three-dimensional hierarchical porous activated carbons for electrochemical energy storage and hydrogen physisorption

Pore structure properties such as specific surface area, pore volume, and pore size distribution are important considerations when using nanoporous carbons as electrochemical energy storage and H ₂ storage materials. In this work, the Quenched Solid Density Functional Theory (QSDFT) analysis is employed to study the nanopore structure of hierarchical porous carbon (HPC) materials derived from bamboo chopsticks (BCS) by adopting a few-step chemical activation method. The effect of carbonization temperature (600–800 °C) and inorganic activator ratio on the surface chemistry and properties of HPC materials are investigated along with the way this influences the energy storage and H ₂ storage performances. The as-prepared materials exhibit high surface area (1439–1940 m ² g ⁻¹) and porosity, which is achieved even with a low KOH:BCS ratio. The supercapacitor (SC) HPC material processed at 800 °C and a KOH:BCS of 2:1, showed a good capacitive performance of 360 F g ⁻¹ at a current density of 0.5 A g ⁻¹ and exhibited a superior rate characteristic along with excellent electrochemical stability. A symmetrical SC reached a specific energy of over 75.3 Wh kg ⁻¹ and a specific power of 375 W kg ⁻¹ in an organic electrolyte. Furthermore, pouch cell type SC devices are fabricated to light LEDs. The hydrogen uptake of all the HPC samples is above 2 wt% (at 77 K and 1 bar) with the highest being 2.3 wt% for the sample processed at 700 °C due to its higher micropore volume. This study proposes a feasible low-cost method to convert waste biomass and exploit the desired hierarchical porous carbon material for multifunctional storage applications.