Synergistic charge and electric field effects on 2D C7N2 nanosheets for enhanced CO2 separation over CH4 and N2: Insights from MD, GCMC, and DFT simulations

Mitigating the greenhouse effect demands the advancement of highly efficient and controllable separation methodologies, alongside the development of robust adsorbing materials. In this study, we propose an innovative strategy involving charge and electric field modulation for enhanced CO2 adsorption and separation, offering adjustable kinetics and reversibility benefits. Employing a combination of MD, GCMC, and DFT simulations, we demonstrate the remarkable CO2 capture performance from CO2/CH4/N2 ternary mixtures on C7N2 nanosheets under varying charge and electric fields conditions. The outstanding CO2 separation capability can be attained through charge regulation, with a maximum CO2 permeance of 3.42 × 107 GPU. Furthermore, the C7N2 slit with 4 e- displayed an excellent CO2 capacity of 24.99 mmol/g at 1 bar and 298 K. Additionally, a reversible CO2 separation performance was achieved under electric field conditions, facilitating the directional accumulation of CO2 molecules. Notably, a synergistic approach combining charge density and electric field (2 e- negative charge and 0.03 a.u.) further boosted CO2 permeance to 2.19 × 107 GPU, 55 % higher than solely 2 e- charged C7N2 nanosheets. The adsorption height, average adsorption energy, OC=O angle, and charge transfer of CO2 molecule on the C7N2 nanosheet were also calculated to elucidate the intrinsic enhancement mechanism. These findings provide valuable guidance for developing advanced materials with highly controllable CO2 capture and separation properties. [Display omitted] •Outstanding synergistic effect of CO2 capture and separation was demonstrated with charge and electric field modulation.•C7N2 nanosheet can be served as an excellent candidate for CO2/CH4/N2 separation at ambient conditions.•The interaction mechanism between the C7N2 surface and CO2 molecule was revealed via MD, GCMC, and DFT simulations.