A green, rapid and size-controlled production of high-quality graphene sheets by hydrodynamic forces

Abstract

Based on a hydrodynamic mechanism, a novel, scalable and rapid production of relatively defect-free graphene nanosheets (GNSs) by a high shear mixer is proposed in this paper. The synergistic enhancement of shear forces and collision effects can result in an effective exfoliation of ultrathin GNSs. Moreover, the productivity and dimension distribution of GNSs can be easily controlled by adjusting hydrodynamic forces. Utilizing the small stator, the concentration of mono- and multi-layer GNSs prepared for 1 h in 40 vol% IPA–water mixtures can reach 0.27 mg ml⁻¹. Almost all GNSs are less than 1 μm in average size and 2 nm in thickness. Furthermore, the mixtures of isopropanol (IPA) and water are low boiling, green, inexpensive, and have excellent solubility for GNSs. The optimal volume fraction of IPA–water mixtures for preparing GNSs is co-determined by the Hansen solubility parameter distance (R_a), surface tension and viscosity. More importantly, graphite particles have strong physical interactions with hydrodynamic forces, but GNSs structure also can remain relatively defect-free. Consequently, this scalable, rapid and high-yield method can be satisfactorily applied in the production of GNSs and other two-dimensional (2D) materials.