Biobased hierarchically porous carbon featuring micron-sized honeycomb architecture for CO2 capture and water remediation

Hierarchically porous carbon (HPC) has exhibited exceptional performance in environmental-related applications; however, the synthesis of high-efficient biobased HPCs remains a challenge because of the inherent structure and chemical composition complexities of biomass. Here, we prepare high-efficient biobased HPC sorbents featuring uniform micron-sized (~20 µm) honeycomb cells and abundant meso- and micropores through combining the selection of biomass precursors and the corresponding synthetic strategies. Cork is selected as the precursor because of its distinctive hollow polyhedral cellular structure and unique chemical composition composed of suberin. ZnCl2 is selected as the activation reagent due to its mild activation effect with less carbon etching and recyclability. The sequential low-temperature pretreatment and ZnCl2 activation processes produce high-efficient HPC sorbent for CO2 capture and water decontamination. Results show that cork-based HPC poses high carbon yield (> 80 wt%), large specific surface area (up to 1853 m2/g), and high pore volume (up to 0.839 cm3/g). Accordingly, cork-based HPC exhibit high CO2 capture performance (e.g., 4.64 mmol/g at 0 °C), superior adsorption capacity for methylene blue (887.7 mg/g) and lead ion (Pb2+, 74.3 mg/g), and fast uptake speed for contaminants (i.e., < 5 min). Moreover, approximately 80% of ZnCl2 can be recycled and reused. This study demonstrates a sustainable and cost-effective process for producing high-efficient HPCs from cork for environmental applications.