Charge- and electric-field-controlled switchable carbon dioxide capture and gas separation on a C2N monolayer

摘要

The use of advanced materials with a high selectivity and easy regeneration to capture CO from a gas mixture is an effective strategy to reduce the greenhouse effect. In this study, we report a comprehensive investigation of CO, N, CH, and H adsorption on a CN monolayer by using DFT calculations. We find that CO is adsorbed weakly on a neutral CN monolayer, and the interaction between CO and CN can be enhanced considerably by applying a negative charge or an external electric field to CN. Moreover, once the charge state/electric field is switched off, CO is released spontaneously from the CN. However, in contrast to the adsorption of CO, the interaction between N/CH/H and CN is physisorption under all of the above conditions. In all, our study demonstrates that the CN monolayer can be used as an excellent material for highly selective and reversible CO capture and gas separation through the strategy of switching on/off its charge state/electric field. In addition, as a 2D material, the CN monolayer possesses a narrow band gap (1.70 eV) that ensures that the application of a charge/electric field can be realized easily experimentally by electrochemical methods.