Matter-substrate interaction of two-dimensional membranes by atomic force driven nanocharacterization

Membranes composed of various 2D materials present compelling commercial prospects spanning filtering, separation, catalysis, and sensing applications, owing to their uniform layered architecture and versatile functionalities. While their performances highly depend on the adhesive substrates, the underlying mechanism is rarely explored and considerable challenges in matching 2D materials with appropriate substrates are therefore presented. In this study, we focus on graphene oxide (GO) as a prototypical 2D material and systematically examine its interactions with diverse substrates, including polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE), alongside PVDF with varying pore sizes. Leveraging GO-modified silicon-based atomic force microscopy (AFM) tips, we elucidate the impact of substrate roughness and adhesion strength on the architecture and performance of GO-based membranes (GOMs). We find that the adhesion force as the predominant determinant, superseding substrate roughness, in GOM formation. Specifically, incomplete GOMs manifest when material-substrate adhesion force falls below 100 nN, while loosely structured GOMs emerge within the range of 150 to 300 nN. Beyond 350 nN, a transition to denser membranes is observed. This work offers valuable guidance for selecting suitable substrates for the formation of 2D materials-based membranes, thereby providing robust support for advancing the development of engineered membrane components.