N/P-Doped MoS₂ Monolayers as Promising Materials for Controllable CO₂ Capture and Separation under Reduced Electric Fields: A Theoretical Modeling

Reversible CO₂ capture with applied external electric fields on solid adsorbents is a promising approach to reduce CO₂ emissions. However, the strengths of the applied electric fields are too high to be performed in practice. So, it is vital to develop new strategies to reduce the strengths of the electric fields. Through the investigation of CO₂ capture on N/P-doped MoS₂ on the density functional theory (DFT) level, we find that the strengths of the electric fields on N/P-doped MoS₂ can be reduced significantly compared with the system without doping. Moreover, the reversible CO₂ capture on them can be controlled by turning on/off the electric field, which is an exothermic reaction without an energy barrier. Especially for N-doped MoS₂ with a larger partial charge distribution difference, the required external electric field for efficient reversible CO₂ capture is 3–64% of the synthesized two-dimensional (2D) materials such as BN, C₂N, C₃N, MoS₂, and N-doped pentagraphene. Additionally, the materials with an applied electric field can separate CO₂ from pre- and postcombustion gas mixtures (CO₂, N₂, CH₄, and H₂). In all, the study provides useful insights that chemical doping on adsorbents is an effective strategy to reduce the required electric field for reversible CO₂ capture and gas separation.