A cost-effective synthesis of heteroatom-doped porous carbons as efficient CO2 sorbents

Abstract

Carbon dioxide release into the atmosphere from fossil fuel burning has been identified as the major reason behind global warming. This has triggered immense interest in developing cost-efficient methods and materials for CO₂ capture in recent years. In this study, benzimidazole was used as an inexpensive and commercially available single source precursor for carbon and nitrogen to successfully produce heteroatom-doped porous carbons (BIDCs) with remarkable CO₂ capture properties. Our synthetic protocol involves solid-state addition of potassium hydroxide to the benzimidazole precursor to prevent its evaporation and subsequent carbonization–activation of the nonvolatile powdery mixture to ensure simultaneous porosity formation and heteroatom doping. The porous structure and heteroatom doping level can be controlled by tuning the KOH/benzimidazole ratio and carbonization temperature. The highest CO₂ uptake values at 0.1 bar (1.60 mmol g⁻¹), 1 bar (5.46 mmol g⁻¹), and 30 bar (28.10 mmol g⁻¹) were realized for three different carbons at 298 K. These diverse CO₂ capture performances originate from a unique combination of surface chemistry and porous architecture for each BIDC. The carbon materials are regenerable and highly promising for CO₂ separation or storage.