Green, fast, and scalable production of reduced graphene oxide via Taylor vortex flow

Abstract

Developing a cost-effective and bulk-scale process for graphene synthesis is essential for its commercialization in a wide range of industrial applications. In this study, for the first time, we used a Couette–Taylor fluid structure with axial flow as a green, rapid, and scalable protocol to synthesize reduced graphene oxide (RGO) flakes. We have determined five different flow characteristics in the laminar, transitional, and turbulent regimes and systematically investigated the effect of flow structure on RGO production. The toroidal vortices ensure the reactants are efficiently mixed, shortening the reduction time of graphene oxide (GO) from several hours to minutes. The results showed that the degree of RGO reduction significantly increased in the Taylor vortex flow (TVF) structure, and decreased in the wavy vortex flow (WVF) regime, because of the secondary instability of the fluid structure. More importantly, the TVF regime results in the synthesis of highly exfoliated and readily water-dispersible RGO products. Finally, the resulting RGO exhibited higher electrical conductivity and mechanical strength than conventional RGO synthesized under circular Couette flow (CCF). Thus, the proposed fluid dynamic protocol may open an effective, potentially cost-competitive, and industrially accessible pathway for producing few-layered RGO flakes for various applications.