Theoretical Study of Controllable Radioactive Xe/Kr Separation on C3N Modulated by Electric Fields

Efficient adsorption/separation of radioactive Xe/Kr is very important and challenging for the rapid development of nuclear energy. Recently, a novel approach for electric field-controlled gas capture/release has been proposed, which provides important advantages such as controllable kinetics and reversibility compared to membrane separation, cryogenic distillation and traditional solid adsorption method. Herein, we for the first time used C₃N for efficient separation of Xe/Kr in the presence of an electric field studied by density functional theory (DFT) method. DFT calculations reveal that a negative electric field can better modulate the surface characteristics of a C₃N nanosheet than a positive electric field, resulting in a transition from physisorption to chemisorption of Xe/Kr on C₃N, and can realize efficient and switchable capture/release of Xe/Kr on C₃N by turning on/off the introduced electric field. The interaction between Xe and the C₃N substrate is more sensitive to an external electric field than that between Kr and C₃N. Under an external electric field of −0.012 au, both the difference in the adsorption energies of Xe and Kr and the corresponding difference rate are large enough, meaning that efficient separation of Xe and Kr on C₃N can be realized. The microscopic mechanism of the interaction between Xe/Kr and C₃N was revealed in terms of adsorption energies, interatomic distances, charge transfers, frontier orbital interactions and projected density of states (PDOSs), providing useful information for the study of adsorption/separation of radioactive Xe/Kr.