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Adsorption of small gas molecules (O 2 , NO, NO 2 and NH 3 ) on transition-metal Cu atom embedded monolayer MoS 2 was investigated by first-principles calculations based on the density-functional theory (DFT). The embedded Cu atom is strongly constrained on the sulfur vacancy of monolayer MoS 2 with a high diffusion barrier. The stable adsorption geometry, charge transfer and electronic structures of these gas molecules on monolayer MoS 2 embedded with transition-metal Cu atom are discussed in detail. It is found that the monolayer MoS 2 with embedded Cu atom can effectively capture these gas molecules with high adsorption energy. The NH 3 molecule acts as electron donor after adsorption, which is different from the other gas molecules (O 2 , NO, and NO 2 ). The results suggest that MoS 2 -Cu system may be promising for future applications in gas molecules sensing and catalysis, which is similar to those of the transition-metal embedded graphene. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dopant Fe atom can be firmly embedded in γ-graphyne (GY-Fe) and break surface chemical inertness. • GY-Fe surface is beneficial to the adsorption of gas molecules (O 2 , CO, NO, NO 2 , and SO 2). • Gas molecules are firmly anchored on GY-Fe plane through the formation of chemical bonds. • Modified γ-graphyne sheet may be a potential substrate to design gas sensor and catalysts. The adsorption behaviors of gas molecules O 2 , CO, NO, NO 2 and SO 2 on the surface of γ-graphyne doped with Fe atom were explored in detailed by first principles calculations. It is found that dopant Fe atoms could be embedded stability into the γ-graphyne plane with the lower binding energy, the modified surface could significantly enhance the adsorption capacity for free gas molecules. Gas molecules are anchored firmly at the surfaces through the formation of chemical bonds with Fe dopant atoms, the typical chemisorption behaviors can be confirmed by the analysis of electronic properties. The O O bond is elongated to 1.412 Å because of the chemical interaction between adsorbed O 2 and dopant surface, the production of activated oxygen radicals maybe used for elimination of toxic gases. The sensing mechanism of GY-Fe was discussed by desorption properties of gas and band structure analysis, we obtained the recovery time about 7.89 s for SO 2 at 398 K. Therefore, this study, maybe provide some helpful informations for the design of graphyne-based gas sensors and catalysts. [ABSTRACT FROM AUTHOR]