ИСТИНА

Self-assembly of graphene-based surface coatings on solids offers a practical alternative to the expensive chemical vapor deposition of graphene. Herein, we report a new facile and scalable approach to form monolayers of graphene oxide (GO) on various solids with a high degree of control over packing density in uniformly flat arrangements of particles. This strategy exploits the interfacial self-assembly of the GO particles at the oil/water interface between the GO hydrosol and non-polar organic solvents. [1] The energy balance for the formation of the interfacial GO monolayer gives negative Gibbs energy that determines thermodynamically favourable spontaneous character of the process. Every GO sheet represents a “Harlequin” particle, which specific bilateral chemistry makes such particle a good interfacial surfactant for the oil/water interface, though only a poor one for the air/water interface. Our method, which requires only a dipper-equipped soaking vessel, offers a time-saving labile route for a large-scale fabrication of the high-quality monolayers of GO on solid supports with different surface energies such as hydrophilic quartz glass or hydrophobic Teflon. The GO particles form uniform flat arrangements on hydrophilic surfaces, whereas on hydrophobic ones the particles undergo partial scrolling to reduce the energy of interfacial interactions. The area of these GO surface coatings can be easily scaled up to tens of centimetres without the loss of control over the thickness and uniformity of resulting films. Microwave irradiation makes it possible to transform the solid-supported GO monolayers into the films of reduced GO showing conductive properties. The efficiency of microwave reduction of these 2D films increases with the ability of the supporting material to absorb irradiation at the microwave frequency: silicon wafer>quartz glass>Teflon. Although the structural perfection of the resulting GO-based surface coatings is far from that achievable by the CVD method, our strategy is useful as a quick-and-cheap method for modifying surface hydrophilicity or electrical properties by the deposition of carbon-based films and for creating the GO templates suitable for further bottom-up assembly of various surface architectures. Acknowledgements The work is supported by Russian Science Foundation (grant №16-13-10512)