Curvature Driven Nanoparticles Decoration of Graphene Membranes

Graphene is extremely resilient to in-plane stresses because of its high Young's modulus[1]; however, it can be easily bent to achieve complex folded structures, known as wrinkles [2]. Such 3D out-ofplane deformations occur both naturally3 and in solution-chemistry processes [4] and, as postulated in the literature, their curvature generate local potential centers with a short-range interaction [5]. The comprehension of the underlying mechanism beyond this phenomenon is fundamental for correlating the topographical properties of wrinkled graphene and its electronic structure. In order to investigate it, gold nanoparticles (NPs) were used to identify if and where they are pinned to wrinkles [6]. Here we report a morphological investigation of silver NPs coated by EG6OH interacting with the surface of wrinkled graphene. The organic coating was used to reduce the metal-graphene interaction. A combination of Scanning Electron Microscopy (SEM) and Scanning Probe Microscopies (namely Atomic Force Microscopy - AFM - and Lateral Force Microscopy - LFM) was used to elucidate the early stage organization of NPs on wrinkled graphene. Firstly, Contact AFM and LFM were used to characterize the morphology of the graphene surface and its wrinkles, respectively. In particular, LFM was able to distinguish clearly three types of wrinkles, characterized by different folded structures [7]. Then, NPs were deposited on the graphene surface by drop casting, observing their organization on the surface by means of Tapping Mode AFM and SEM. Correlative images show that NPs diffuse on the graphene surface reaching wrinkles, then they diffuse along the topographic step formed by the wrinkle as long as a defect is met. The type of wrinkle seems not to affect this behavior. References 1. Lee C et al. Science 2008;321:385-88 2. Vandeparre H et al. Phys Rev Lett 2011;106:224301 3. Meyer JC et al. Nature 2007;446:60-3 4. Zhang J et al. Phys Rev Lett 2010;104:166805 5. Guinea F et al. Phys Rev B 2010;81:035408 6. Pacakova B et al. Carbon 2015;95:573-79 7. Kim K et al. Phys Rev B 2011;83:245433