Electrically Conductive Thin Films Derived from Bulk Graphite and Liquid–Liquid Interface Assembly

Abstract

Confinement of particles to fluid–fluid interfaces provides a unique interaction environment, allowing the directed assembly of particles using lateral capillary forces. The particle laden interfacial layers can be deposited onto a variety of substrates for the fabrication of thin film coatings, designed to have structural or functional properties resulting from the interface-specific structures. For the fabrication of electrically conducting films and specifically graphene-based coatings, interfacial deposition techniques could offer a low cost and environmentally favorable alternative to conventional gas phase production methods, with possibly a broader choice of substrates. In this work liquid-phase electrochemical exfoliation is used to produce platelets of few-layer graphene from bulk graphite which are directly introduced to the water–air interface. These interfaces are characterized through compression experiments and interfacial shear rheology to probe the mechanical properties of the resulting monolayer films and identify mechanical percolation. Further, in situ measurements of electrical conductivity are integrated as a direct indication of electrical percolation. This directly verifies sufficient film quality as an important characteristic of the deposition process. Once deposited on a solid substrate, these films retain their electrical conductivity. But the mechanical properties of the films allow for facile production of freestanding microporous graphene membranes.