Catalytic CO<sub>2</sub> Capture via Ultrasonically Activating Dually Functionalized Carbon Nanotubes.

Gao, Yangyan; He, Xin; Mao, Keke; Russell, Christopher K; Toan, Sam; Wang, Aron; Chien, TeYu; Cheng, Fangqin et al. · ACS Nano · 2023

basic_science · Level V

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Abstract

High energy consumption and high cost have been the obstacles for large-scale deployment of all state-of-the-art CO<sub>2</sub> capture technologies. Finding a transformational way to improve mass transfer and reaction kinetics of the CO<sub>2</sub> capture process is timely for reducing carbon footprints. In this work, commercial single-walled carbon nanotubes (CNTs) were activated with nitric acid and urea under ultrasonication and hydrothermal methods, respectively, to prepare N-doped CNTs with the functional group of -COOH, which possesses both basic and acid functionalities. The chemically modified CNTs with a concentration of 300 ppm universally catalyze both CO<sub>2</sub> sorption and desorption of the CO<sub>2</sub> capture process. The increases in the desorption rate achieved with the chemically modified CNTs can reach as high as 503% compared to that of the sorbent without the catalyst. A chemical mechanism underlying the catalytic CO<sub>2</sub> capture is proposed based on the experimental results and further confirmed by density functional theory computations.