Catalyst-free growth of single- to few-layered graphene on ionic liquid surfaces at room temperature

Abstract

Environmentally friendly, energy-saving and efficient preparation of graphene is a long-term pursuit in the field of 2D materials. Here, single- to few-layered graphene is successfully fabricated on ionic liquid surfaces by a modified arc-discharge evaporation method without the assistance of catalysts and at room temperature. When the arc-discharge synthesis is conducted with direct currents of I = 75–150 A, ramified carbon atomic aggregates containing various diamond grains with a hexagonal lattice structure form on the liquid substrates. If the currents range from I = 165–180 A, however, single- to few-layered graphene films with an average size of 200–300 nm grow on the liquid surfaces. The films may be transferred to arbitrary substrates from the liquid surfaces conveniently and completely, which is significant for future applications. Based on the experimental results, the growth mechanism of the graphene films is presented.