Decorating carbon nanotubes with different ratios of graphene quantum dots via ultrasonication as a potential material for CO2 capture

Abstract

ABSTRACT The harmful impacts of carbon dioxide (CO2) emissions are represented mainly in global warming as a major greenhouse gas, health problem issues, and pollution. As a result, there is currently worldwide interest in developing efficient adsorbents with high adsorption capacity for CO2 gas. In this work, the adsorbent nanocomposites were synthesized from different loadings of graphene quantum dots (10, 20, and 30%) with carbon nanotubes (CNTs) using the ultrasonication method. The prepared nanocomposites were characterized by XRD, HR-TEM UV-Vis, Raman, and BET, techniques to investigate their chemical and physical characteristics. The samples reveal a high surface area and porosity. The optical band gap was calculated for the nanocomposites; it decreased upon increasing the ratio of the GQDs, since the 30% GQDs/CNT show an Eg of about 1.93 eV compared to 2.1 eV for the 10% and 20% GQDs/CNTs. The samples of 20% and 30% GQDs/CNTs revealed the highest active site density; furthermore, they showed the best performance for CO2 gas capture of about 24.6 mmol. g−1 and 25 mmol. g−1, which makes these nanocomposites efficient adsorbents for CO2 emissions.