Selective Etching of Silicon from Ti3SiC2 (MAX) to Obtain 2D Titanium Carbide (MXene)

Transmission electron microscopy (TEM) shows that delaminated solutions consist of both, single flakes and few-layer stacks. The transparency of the flake suggests the flake is a single layer, when the atomic weight of Ti is taken in consideration. Acidic, fluoride-containing etchant solutions are commonly used to selectively remove the A-element layers. These chemical etching processes result in surfaces often functionalized with -O, -F or -OH groups. The hydrodynamic size and negative z-potential demonstrate the stable, colloidal nature of the solutions and the absence of large amounts of agglomerates. These values are in agreement with TEM and compare well to sonicated Ti₃C₂ derived from Ti₃AlC2.