Synthesis of Boron-Doped Porous Carbons from Water Chestnut Shells and Their Roles in CO ₂ Capture Applications

Porous carbons have garnered significant attention for their excellent performance in carbon capture applications, which is attributed to their distinctive textural and physicochemical characteristics. The design of heteroatom-doped porous carbons derived from renewable biomass precursors represents a promising direction for sustainable materials development. By integrating eco-friendly synthesis strategies with cost-effective processing routes, such materials can be tailored to exhibit enhanced porosity, surface chemistry, and adsorption capacity. In this context, the current study presents the synthesis of boron-doped porous carbons via a KOH activation process, utilizing water chestnut shells as the carbon precursor and boric acid as the boron source. The synthesized porous carbons exhibit a well-developed porous structure and rich boron functionalities. Their performance was systematically evaluated for CO₂ adsorption. Notably, the maximum CO₂ adsorption capacities reached 4.82 mmol g⁻¹ and 7.01 mmol g⁻¹ at 25 °C and 0 °C under 1 bar pressure, respectively, which is primarily attributed to the well-developed narrow microporosity, with boric acid playing an indirect role in regulating pore formation during the activation. Finally, the underlying mechanisms contributing to the superior CO₂ adsorption performance are comprehensively discussed. In this study, boron-doped porous carbons derived from water chestnut shells exhibit a strong potential as sustainable and efficient sorbents for carbon capture.