Theoretical investigation of the optical and electronic properties of surface engineered V 2 N MXene

Abstract

In this work, density functional theory is utilized to explore the impact of surface adsorption of (O, S, Se and Te) on the structural, electronic and optical properties of two-dimensional vanadium nitride (V 2 N) MXene and the results are compared with pristine V 2 N MXene. Our calculations show that V 2 NSe 2 MXene has the most stable structure among all the studied structures. Adsorption energy computations reveal that all terminal groups on the surface of the pristine V 2 N tightly attach to the V atoms. A metallic to semiconductor transition is observed in all the considered V 2 NT 2 (T=O, S, Se and Te) MXene structures. Among them, oxygen, selenium and tellurium adsorbed V 2 N shows a direct bandgap of 0.45, 0.86 and 0.53 eV, respectively. However, in case of sulphur adsorbed V 2 N MXene, an indirect bandgap of 1.19 eV is observed. This study also reports the effect of surface adsorption on the optical properties and dielectric constant of V 2 NT 2 (T=O, S, Se and Te). The results reveal a larger absorption in visible region as well as in ultraviolet region for all the computed structures except oxygen adsorbed V 2 N MXene as compared to pristine V 2 N MXene monolayer, which indicates the significance of surface adsorption on the optical properties of the studied MXene. Additionally, a very low reflectivity has been seen in all the V 2 NT 2 MXene structures as compared to pristine V 2 N. Our findings demonstrate the potential of these surface adsorbed V 2 N MXene materials in novel light-electron conversion devices.