Self-Assembly of Metal Oxide Nanoparticles in Liquid Metal toward Nucleation Control for Graphene Single-Crystal Arrays

Abstract

We have achieved the spontaneous assembly of alumina nanoparticles on a liquid metal surface and further synthesized a very-large-scale graphene single-crystal array. The effective electrical field established as a result of the electrical charge of the alumina nanoparticles in the liquid metal ensures the ordered self-assembly of the alumina islands and lays the foundation for precise spatial control of graphene nucleation, leading to the formation of graphene single-crystal arrays. In addition, controlling the density of the alumina in the liquid metal can precisely tune the periodicity of the arrays. This simple strategy, which is unlike the usual solid/aqueous solution system, opens up new territory for nanoparticle assembly. Focusing on the origin of the nanoparticle interaction that drives the self-assembly of ordered structure in the liquid metal system is a promising avenue for triggering more interesting applications. Self-assembly of nanoparticles has offered a playground not only for achieving ingenious structures but also for developing tunable collective properties. The interaction and self-assembly of nanoparticles in aqueous solution systems have been well understood over the past decades. However, the assembly of nanoparticles in liquid metal is rarely explored. Here, we present the self-assembly of metal oxide nanoparticles into an ordered structure in liquid metal. By utilizing metal oxide particle arrays as the nucleation sites, we constructed very-large-scale graphene single-crystal arrays via chemical vapor deposition, which will promote their future industrial application in integrated optics and electronics. The proposed concept of spontaneous construction of nanoparticles in a liquid metal system provides a new perspective on self-assembly behavior and will extend the related potential applications. Self-assembly of nanoparticles is efficient for constructing ingenious structures and developing collective properties. The interaction and self-assembly of nanoparticles in aqueous solution systems are well understood. However, the assembly of nanoparticles in liquid metal is rarely explored. Here, we present the self-assembly of metal oxide nanoparticles in liquid metal. By utilizing metal oxide particle arrays as the nucleation sites, we constructed very-large-scale graphene single-crystal arrays, which will promote their future industrial application in integrated optics and electronics.