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.