Versatile tailoring of electronic conduction in 2D transition metal carbides via surface termination engineering: Nonequilibrium quantum mechanical study

• MXene exhibits significant electric conductive variation relying on surface states. • Complete elimination of surface termination boosts up MXene’s electric conductance. • Surface termination coverage predictably determines MXene’s conductive degree. • The largest electric resistance is obtained at ∼ 50 % of surface termination coverage. Two-dimensional (2D) transition metal carbides (MXenes) are promising electron conducting materials. Noticeably, they intrinsically have surface functionality and the control of surface termination has proven robust and efficient for modulating MXenes’ mechanical and optical properties. However, its effects to MXenes’ electronic conduction have rarely been studied. Using nonequilibrium quantum mechanical simulations, here we showed that surface termination engineering can be powerful means of regulating the electric conductance of Ti 3 C 2 T x MXenes. Two extreme fully oxygen-terminated (Ti 3 C 2 O 2 ) and bare (Ti 3 C 2 ) surfaces were considered since oxygen is one of dominant surface terminations of MXenes. We revealed that Ti 3 C 2 are superior electric conductors compared to Ti 3 C 2 O 2 , showing five-times high performance in our system. We further explored this issue by gradually increasing the surface oxygen-terminated degree of the scattering region of Ti 3 C 2 . The conductance underwent an S-like variation, representing significant 7.5-times tunability showing minimum at the oxygen-termination portion of 50%. Ti 3 C 2 O 2 with various surface bareness also exhibited significant and dynamic conduction variation with minimum around 40%, but in a quantitatively different manner due to the use of oxygen-terminated electrodes.