Synthesis of (V2/3Sc1/3)2AlC i-MAX phase and V2−xC MXene scrolls

Abstract

We report the synthesis and characterization of a new laminated i-MAX phase, (V_2/3Sc_1/3)₂AlC, with in-plane chemical ordering between the M-elements. We also present evidence for the solid solution (V_2−xSc_x)₂AlC, where x ≤ 0.05. Chemical etching of the Al and Sc results in a two-dimensional (2D) MXene counterpart: V_2−xC from the latter phase. Furthermore, etching with HF yields single-sheet MXene of flat morphology, while LiF + HCl gives MXene scrolls. We also show a 4× reduction in etching time for (V_2−xSc_x)₂AlC compared to V₂AlC, suggesting that traces of Sc changes the phase stability, and make the material more susceptible to etching. The results show a path for improved control of MXene synthesis and morphology, which may be applicable also for other MAX/MXene systems.