Graphene / hexagonal boron nitride composite nanoparticles for 2D printed heteros structures

A peculiarity of the present study is the use of plasma for the creation of the flakes of graphene and hexagonal boron nitride (h-BN) without using substrates and catalysts. Application of the direct-current arc torch plasma jets provides the advantages of the property controllability and mass production of both types of flakes. The conditions for the formation of composite nanoparticles from graphene and h-BN flakes in suspension were worked out. Morphology and structure of the composite nanoparticles are found to change with an increase of graphene content in composition from (1) the multi h-BN clusters with a random structure on graphene to (2) the graphene flakes covered with the vertically arranged h-BN flakes, then (3) the graphene flakes encapsulated with a monolayer of h-BN flakes, and, at last, (4) the h-BN clusters decorated with graphene scrolls. Practically in all cases, the composite nanoparticle size was 150 -300 nm, this size corresponds to the ability to use them for inkjet 2D printing. The electrical properties of the films created from these composite nanoparticles are also strongly changed depending on their structure. The composite G:h-BN with content (10–6):1 demonstrates non-linear current-voltage characteristics with strong hysteresis (up to 4 orders of magnitude), whereas I-V curves for films with lower or higher graphene content are linear. The temperature dependencies of current in such composite layers show the transport with the activation energy of 27-34 meV most likely connected with bandgap formation due to graphene – h-BN van der Waals interaction. The strongly increased photocurrent was also observed for the composite films.