PERIODICALLY WRINKLED GRAPHENE FOR DESIGN OF ORGANIZED CLAY STRUCTURES

Layered material-carbon nanocomposites are very promising for ‘green’ applications in the energy storage or chemical (gas) sensing. One of the very interesting nanocomposites could be the clay-graphene system [1], with the graphene working as an electrode. Fabrication of ordered clay structures on graphene can be done using the self-assembly of clay particles. To increase the efficiency of the fabrication process targeting the defined design of clay structures on graphene, wrinkled graphene can be used rather than standard flat graphene transferred over the flat substrate. We are showing two types of wrinkled graphene structures: homogeneously wrinkled graphene [2, 3] and graphene with large arrays of parallel equidistantly separated long wrinkles [4]. Both types of graphene wrinkle networks were made using the pre-patterned substrates; the Si/SiO2(300 nm) substrate decorated with the superparamagnetic nanoparticles [2, 3], and hexagonal array of the SiO2 nanopillars [4]. The wrinkle hierarchy can be well controlled for both sample types. Area covered by wrinkles on the nanoparticle-supported graphene increases linearly with the nanoparticle density, forming typical wrinkle shapes with the wrinkles propagating in all directions [2, 3]. On the contrary, the networks of parallel equidistantly separated long wrinkles (Fig. 1) found on the nanopillars-supported graphene are formed on the line defects in graphene (grain boundaries). If no line defect is present, the wrinkles on nanopillar-supported graphene form networks qualitatively comparable with the wrinkles on nanoparticle-supported graphene [4]. Both wrinkle network types are promising candidates for the smart substrates allowing formation of the clay structures with predictable and defined geometry, such as the well-separated clay islands or long parallel lamellas. Fig.1. Formation of the aligned wrinkle networks induced by the graphene line interfaces (marked with green arrows); a) AFM topography and b) phase images. As seen, the graphene line interface is barely observable in the AFM topography (a) and the position of the interface cannot be determined from the cross-sections of the topography. (c, d) HRSEM images of the nanopillar arrays. (e, f) 3D AFM topography visualization of the wrinkled graphene on the top of the nanopillar arrays. [1] Ruiz-Garcia C., Darder M., Aranda P., Ruiz-Hitzky E. (2014). Toward a green way for the chemical production of supported graphene using porous solids. J. Mater. Chem. A, 2009-2017. [2] Pacakova B.,. Vejpravova J., Repko A. et al. (2015). Formation of wrinkles on graphene induced by nanoparticles: Atomic force microscopy study. Carbon, 573-579. [3] Vejpravova J., Pacakova B., Endres J. et al.. (2015). Graphene wrinkling induced by monodisperse nanoparticles: facile control and quantification. Sci. Rep., 15061. [4] Pacakova B., Verhagen T., Bousa M. et al. (2017). Mastering the Wrinkling of Self-supported Graphene. Sci. Rep. 7, 10003.