Tailored GO nanosheets for porous framework to high CO2 adsorption

Abstract

The 2D graphene oxide (GO) is promising for CO2 adsorption, benefitting from its theoretically high specific surface area and abundant oxygen-containing groups. However, the GO nanosheets aggregation renders the loss of CO2 adsorption site, reducing the CO2 adsorption capability. To tackle this issue, we propose of tailoring physical and chemical structures of the GO nanosheet by etching and oxidation, which concurrently enhance the specific surface area and oxygen-containing functional groups. The etching step creates additional in-plane nanopores in the GO nanosheet and uncovers the inaccessible sites on the GO nanosheet. The oxidation step produces more oxygen-containing groups, i.e., active sites, to intensify the CO2 adsorption of GO nanosheets. Resultantly, through enhancing pore volume and interaction between CO2 and oxygenic functional group, the adsorption capacity of CO2 is promoted. As such, the CO2 adsorption capability of GO nanosheets is significantly enhanced. The optimized oxidized porous GO nanosheets are employed for CO2 adsorption after Ca2+ crosslinking, which realizes a high CO2 adsorption capability of 2.5 mmol/g at 298 K, 1 bar. Together with its prominent running stability, the fabricated porous GO-based adsorbents show great potential for CO2 capture to mitigate the current greenhouse gas dilemma.