Key points are not available for this paper at this time.
The cover shows a scanning electron microscopy (SEM) image of graphene-like crystals of Ti3C2 called MXene. On page 4248 Yury Gogotsi, Michel W. Barsoum, and co-workers describe the exfoliation of Ti3AlC2, a member of a 60+ group of layered ternary carbides and nitrides known as MAX phases, by etching the aluminum out in HF. This approach can be used to synthesize other 2D carbides and nitrides. Colored SEM image by Babak Anasori, Drexel University.
Naguib et al. (Wed,) studied this question.