Carbon dioxide adsorption of two-dimensional Mo2C MXene

In this paper, the CO2 adsorption behaviors of Mo2C MXene were explored for the first time. Two-dimensional (2D) Mo2C MXene samples were prepared by hydrothermal etching in four different solutions (LiF, NaF, KF or NH4F with HCl). The sample made by LiF + HCl etching exhibited the highest capacity of 3.66 mmol g-1, which is consistent with theoretical calculation that Mo2CO2 decorated by Li has stronger interaction with CO2 than those of Na and K. Although Mo2C MXene has low specific surface area (SSA, 4.9-8.9 m2 g-1) as compared with those of Ti3C2 (21 m2 g-1) and V2C (9 m2 g-1) MXenes, Mo2C MXene possesses better performance on CO2 capture than Ti3C2 (1.33 mmol g-1) and V2C (0.52 mmol g-1) MXenes at 4 MPa. This is because the CO2 adsorption of Mo2C MXene is mainly physical absorption formed by the capillary condensation in mixed pores (micropores and mesopores) and slitlike pores between two Mo2C MXene flakes. Besides, the CO2 adsorption on the surface of Mo2C MXene with functional groups (O or F) shows a current of chemisorption feature. This work indicates that Mo2C MXene is a promising candidate for CO2 capture and storage material.

Automated summary

This study explores the CO2 adsorption behaviors of Mo2C MXene for the first time. The sample prepared with LiF + HCl etching exhibits the highest capacity and stronger interaction with CO2. Despite having a lower specific surface area compared to other MXenes, Mo2C MXene shows better CO2 capture performance due to physical absorption formed by capillary condensation in mixed pores and slitlike pores. Additionally, the CO2 adsorption on the surface of Mo2C MXene with functional groups (O or F) shows a chemisorption feature.