Transition metal-modified Θ-graphene controls CO2 capture and separation under electric field modulation

The increasing concentration of CO${}_2$ gas in the atmosphere causes great pressure to the environment, so it is urgent to find efficient CO${}_2$ capture materials. In this study, the adsorption behavior of CO${}_2$ on 3$d$ transition metal (TM) modified $\Theta$-graphene (TM-$\Theta$) was studied by first-principles calculation, and the synergistic effect of electric field was considered. The adsorption performance of TM-$\Theta$ towards CO${}_2$ is significantly enhanced. Ti-$\Theta$ (−1.63 eV) and V-$\Theta$ (−1.76 eV) are the most outstanding, and the adsorption energy is increased to about 10 times of the original $\Theta$-graphene (−0.17 eV). In addition, the reversible adsorption of CO${}_2$ on Ti-$\Theta$ is expected to be achieved by controlling the electric field. More importantly, Ti-$\Theta$ exhibits high selectivity in separating CO${}_2$ from the gas mixtures (CO${}_2$/H${}_2$/CH${}_4$) under the applied electric field. Ti-$\Theta$ has potential applications in recyclable CO${}_2$ capture materials, and external electric field can facilitate the development of CO${}_2$ capture, storage and separation technologies.