Janus-like, Asymmetric graphene Nanosheets for Ultrafiltration and Sieving.

Research Project, 2018 – 2021

We will study a new material called Janus graphene, composed of graphene monolayers having different chemical functionalization on different faces of the sheet. The sheets will be stacked in a controllable and reproducible way forming 2-dimensional pores with nanometric width and a length spanning from 100 nm to 100 microns. The pore width will be tuned on the Angstrom scale using suitable molecular spacers covalently bounds to the sheets. Small molecules such as water shall intercalate and diffuse in these 2D porous materials driven by supramolecular, weak interactions; the asymmetric chemical environment of the pores will influence orientation, conformation and optoelectronic properties of the diffusing molecules. Different classes of chemical groups will be tested as spacers: hydroxyl, carboxyl and epoxy groups typical of graphene oxide, linear and branched alkyl chains, spacers bearing aromatic molecules able to interact with graphene sheets, and “molecular switches”, able to undergo a reversible trans–cis isomerization triggered by light or an electric field, to obtain “functional” membranes whose permeability shall be switched on/off. The diffusion of molecules in such 2-dimensional pores will be studied using an original approach based on a combination of neutron scattering, Kelvin Probe Microscopy and tip-enhanced Raman scattering (TERS), as well as computer modelling.