Balsa Wood-Derived Carbon Enriched with Hydroxyl Functional Groups for Efficient CO₂ Sorption

Developing efficient sorbent systems with a high CO2 adsorption capacity and ease of regeneration is crucial for carbon capture. This work presents a bioinspired approach using three-dimensional (3D) porous carbon derived from abundant Balsa wood. CO2 on these materials has been systematically investigated using kinetic characterization, in situ Fourier-transformed infrared (FTIR) spectroscopy, and theoretical calculations. The 3D carbon materials possess a high surface area and abundant hydroxyl (OH) groups, which act as basic sites to interact with acidic CO2, significantly enhancing the CO2 adsorption capacity. Specifically, KOH-treated Balsa carbon could achieve a CO2 adsorption capacity of 4.1 mmol g–1 at 600 mbar, outperforming other carbon-based adsorbents. In situ FTIR spectroscopy confirmed that CO2 adsorption is predominantly chemisorptive, forming carbonate and bicarbonate species. Efficient CO2 desorption under mild conditions (<85 °C) and negligible performance degradation over 11 cycles indicate good stability and reusability. Density functional theory calculations supported the experimental findings, showing favorable chemisorption with an adsorption energy of −0.64 eV for an OH-functionalized model carbon surface. This study highlights the importance of surface functionalization in enhancing the CO2 adsorption capacity and provides insights for designing advanced carbon-based sorbents. This work also demonstrates the potential of 3D porous carbon from Balsa wood as a high-performance CO2 sorbent, offering a sustainable and efficient solution for carbon capture and contributing to global efforts to reduce atmospheric CO2 and mitigate climate change.