N-doping enabled defect-engineering of MoS2 for enhanced and selective adsorption of CO2: A DFT approach

A density functional theory study was conducted to analyze CO2 adsorption on defective and non-defective MoS2 surfaces with or without nitrogen doping. The MoS2_1V(S) and MoS2_1V mo _3N(S) were found exhibiting outstanding adsorption activity and stability, which is linked to an enhanced electron charge on the surface in the presence of vacancies and N species that alters strength and type of interactions with CO2 molecules. Results showed the dissociative chemisorption of CO2 on the MoS2_1V, and a significantly enhanced physisorption of CO2 on the MoS2_1V(Mo)_3N(S), which displays an adsorption energy of -1.818 eV compared with -0.139 eV of the pristine MoS2 surface. Meanwhile, the MoS2 _1V(S) exhibits an excellent selective adsorption of CO2 over N-2 and H2O, with the highest adsorption ratio of 5.1 and 3.5, respectively. Partial dissociation of CO2 to CO over the MoS2_1V(S) is also observed and attributed to increased covalent attractions at the vacant site, while the improved CO2 physisorption over the MoS2_1V(Mo)_3N(S) is attributed to the enhanced electrostatic interactions at the vacancy site due to N doping. These findings are confirmed by the computed vibrational frequencies of CO2 bound on these surfaces. The N-doping enabled defect engineering of MoS2 is proved effective and enhanced selective adsorption of CO2.

Automated summary

The study highlights that nitrogen doping enhances the CO2 adsorption activity and stability of MoS2 surfaces, leading to improved selective adsorption of CO2 by altering the electron charge on the surface caused by vacancies and nitrogen species.