A novel C6N2 monolayer as a potential material for charge-controlled CO2 capture

Abstract

Nowadays, carbon emissions are becoming more and more serious, and therefore it is essential to explore advanced materials with high selectivity and simple operation for capturing and sequestrating CO₂. Hence, a new C₆N₂ monolayer is explored by using the particle swarm optimization (PSO) algorithm for structural search, and then the ability of the charge-controlled C₆N₂ monolayer to capture CO₂ is investigated by the first principles simulation. The results show that the binding strength of CO₂ on negatively charged C₆N₂ can be significantly increased by injecting extra electrons. The process of CO₂ capture and release on negatively charged C₆N₂ is reversible, and thus it can be easily controlled by turning on and off the charges carried. More importantly, the CO₂ capture capacity of C₆N₂ is 5.00 mmol g⁻¹, which is better than 2.90 mmol g⁻¹ of N-doped carbons under 1 atm at 25 °C. In addition, the negatively charged C₆N₂ monolayer is highly selective for the separation of CO₂ from CH₄, H₂, and N₂ mixtures. Based on these remarkable results, C₆N₂ is a promising charge-controlled CO₂ capture material with reversibility, high capacity and selectivity.