Spacer-Assisted Amine-Coiled Carbon Nanotubes for CO2 Capture

Abstract

Architecture of a DNA-wrapped carbon nanotube (CNT) inspires rational design of a polymer-wrapped CNT effective for CO2 capture. Polyethyleneimine (PEI) selected as a spiral wrapper of CNT is modified by insertion of spacer molecules loaded with amino groups such as siloxanes and purine to enhance the CO2 capture performance. A porous adsorbent made by packing these functional nanowires (e.g., PEI-purine-CNT) reveals CO2 uptake as large as 3.875 mmol/g. Adsorbent materials from this biomolecule-inspired design drop the adsorption heat to 29.00 kJ/mol if secondary and tertiary amines are adopted, besides the primary one, a value that is one-third of the absorption heat of an industrially deployed, liquid absorbent of CO2. The corresponding adsorption and desorption kinetics agree with an Avrami model, indicating that both processes involve multiple sorption pathways. Furthermore, PEI-purine-CNT maintains its adsorption capacity after 50 adsorption-desorption cycles, implying a great potential for carbon capture from smokestacks and air in a stable and cyclic manner.