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.