Self-assembly of the deposited graphene-like nanoparticles and possible nanotrack artefacts in AFM studies

Abstract

Abstract Atomic force microscopy (AFM) is widely used for structural characterization of 2D materials. We report here on the appearance of linear pseudo-structures of subnanometer height (‘nanotracks’), observed in AFM images of 2D-nanoparticles of graphene, MoS2, WS2, BN, synthesized by the mechanochemical technique and deposited from dispersions on the mica surface. It is stated that the nanotracks appear as a result of nanoparticle displacement on the surface under the influence of the AFM tip during scanning. The appearance of the nanotracks is caused by a high relative concentration of monolayer nanoparticles in the prepared dispersions; their bulk aggregation; subsequent destruction of the aggregates by the AFM probe with formation of the nanoparticles weakly bound to the substrate. A method is proposed how to distinguish monolithic particles from granulated aggregates, as well as a technique to prevent their displacement during measurements. The possibility is considered of using AFM to develop effective nanolubricants and provide their precise nanoscale deposition on the specified surface areas.