In their paper, the researchers discuss in detail graphene delamination from platinum (Pt) surfaces using electrochemical methods. They show that water intercalation between graphene and a Pt surface is critical to achieve a successful graphene delamination using an electrochemical method.
They also demonstrate that intercalation effects can occur between graphene and a target wafer, resulting in unwanted graphene delamination effects.
Exposing a platinum/graphene sample for several days to ambient conditions or submerging it in warm ultrapure water gradually changes the graphene surface morphology and varies the chemical composition of the graphene/Pt interface.
The results are consistent with water intercalation, which progressively develops at the interface. This intercalation process is essential to obtain a successful electrochemical graphene delamination procedure.
Furthermore, the team established a direct graphene transfer process on the basis of interfacial water between graphene and the CVD growth substrate and of avoiding water intercalation between the hydrophobic target wafer and graphene.
Such a direct graphene transfer avoids polymer contamination (no temporary support layer) and etching of the catalyst metal. As a result, recycling of the growth template becomes feasible.
"Since the interaction between graphene and water is comparable to the interaction between MoS2 and water, a transfer procedure based on controlling water intercalation might also work for other 2D materials like MoS2," the authors conclude their report. "As a result, the proposed transfer process might even open the door for the predicted atomic-scale interlocking-toy-brick stacking of different hydrophobic 2D materials."