Direct formation of MXene domains and compositional defects in magnetron sputtered V2AlC-AlOx heterostructures revealed by theory and experiments

Abstract

We report on direct formation of nanometer-sized V₂C and novel V₃C₂ MXene domains at V₂AlC-AlO_x heterostructure interfaces synthesized by physical vapor deposition. Their formation is facilitated by local Al deintercalation from V₂AlC MAX phase into AlO_x enabled by the selected architecture maximizing the contact area of V₂AlC MAX phase and AlO_x. Furthermore, the formation of VC, V₃AlC₂, V₅AlC₄, V₇AlC₆, V₈AlC₇, and V₁₀AlC₉ compositional defects is observed by aberration-corrected transmission electron microscopy and formation thereof is, together with the MXene formation, rationalized by density functional theory calculations. The applied synthesis approach thus shows the potential to be a step towards the chemical etching-free production of MXenes and can be further extended to other MXene compositions, since the A elements typically have a large affinity to oxygen.