CO2 Capture, Separation and Reduction on Boron-Doped MoS2, MoSe2 and Heterostructures with Different Doping Densities: A Theoretical Study

Designing high-performance materials for CO2 capture and conversion is of great significance to reduce the greenhouse effect and alleviate the energy crisis. The strategy of doping is widely used to improve activity and selectivity of the materials. However, it is unclear how the doping densities influence the materials' properties. Herein, we investigated the mechanism of CO2 capture, separation and conversion on MoS2, MoSe2 and Janus MoSSe monolayers with different boron doping levels using density functional theory (DFT) simulations. The results indicate that CO2, H-2 and CH4 bind weakly to the monolayers without and with single-atom boron doping, rendering these materials unsuitable for CO2 capture from gas mixtures. In contrast, CO2 binds strongly to monolayers doped with diatomic boron, whereas H-2 and CH4 can only form weak interactions with these surfaces. Thus, the monolayers doped with diatomic boron can efficiently capture and separate CO2 from such gas mixtures. The electronic structure analysis demonstrates that monolayers doped with diatomic doped are more prone to donating electrons to CO2 than those with single-atom boron doped, leading to activation of CO2. The results further indicate that CO2 can be converted to CH4 on diatomic boron doped catalysts, and MoSSe is the most efficient of the surfaces studied for CO2 capture, separation and conversion. In summary, the study provides evidence for the doping density is vital to design materials with particular functions.