Size fractionation of graphene oxide sheets assisted by circular flow and their graphene aerogels with size-dependent adsorption

Abstract

Lateral dimensions of graphene oxide (GO) sheets are acknowledged to critically influence the properties of macroscopic GO-based materials. However, restricted by current size fractionation technologies, it is still a great challenge to obtain GO sheets in a relatively narrow size distribution by a simple method. Here, we introduce a facile size fractionation of GO sheets assisted by circular flow. With the help of hydrogen gas (H₂) bubbles generated from a metallic replacement reaction, continuous turbulence forms a circular flow in a special tubular container to make it possible to fractionate different sized GO sheets. By using this process, crude GO (CGO) sheets can be facilely separated into three size ranges, namely LGO (>20 μm), MGO (2–20 μm) and SGO (<2 μm). Another advantage is that the separation approach can simultaneously remove residual graphite oxides. Furthermore, graphene aerogels made of LGO precursors (LGA) show better absorptivity than those of CGO, MGO and SGO precursors.