Ca-Embedded C2N: an efficient adsorbent for CO2 capture

Abstract

Carbon dioxide as a greenhouse gas causes severe impacts on the environment, whereas it is also a necessary chemical feedstock that can be converted into carbon-based fuels via electrochemical reduction. To efficiently and reversibly capture CO₂, it is important to find novel materials for a good balance between adsorption and desorption. In this study, we performed first-principles calculations and grand canonical Monte Carlo (GCMC) simulations, to systematically study metal-embedded carbon nitride (C₂N) nanosheets for CO₂ capture. Our first-principles results indicated that Ca atoms can be uniformly trapped in the cavity center of C₂N structure, while the transition metals (Sc, Ti, V, Cr, Mn, Fe, Co) are favorably embedded in the sites off the center of the cavity. The determined maximum number of CO₂ molecules with strong physisorption showed that Ca-embedded C₂N monolayer is the most promising CO₂ adsorbent among all considered metal-embedded materials. Moreover, GCMC simulations revealed that at room temperature the gravimetric density for CO₂ adsorbed on Ca-embedded C₂N reached 50 wt% at 30 bar and 23 wt% at 1 bar, higher than other layered materials, thus providing a satisfactory system for the CO₂ capture and utilization.