Amine-Functionalized Activated Carbon Monoliths by 3D Printing for Direct Air Capture

Direct air capture (DAC) is an emerging technology that supports mitigating climate change. However, its large-scale deployment is hindered by high energy demands and material costs. In this study, we present a novel porous sorbent material for DAC using 3D-printed activated carbon monoliths functionalized with an aminosilane compound. The monoliths were fabricated via direct ink writing and subsequently modified with 3-aminopropyltriethoxysilane (APTES) to introduce chemisorption sites for CO₂. Structural and chemical analyses confirmed successful grafting of amines without compromising the monolithic architecture. The resulting monoliths demonstrated enhanced CO₂ uptake at atmospheric concentrations (0.25 mmol g^-1 at 0.04 kPa). IR spectroscopy revealed that the functionalized monoliths chemisorb CO₂ from ambient air as ammonium carbamate. Chemisorbed CO₂ can be desorbed at a temperature of 75°C, indicating a low energy requirement for a DAC process. To the best of our knowledge, this paper is the first published application of aminosilane-functionalized activated carbon for DAC, highlighting its potential as a cost-effective and scalable sorbent material.