Green and High-Efficiency Production of Graphene by Tannic Acid-Assisted Exfoliation of Graphite in Water

A green and high-efficiency method was developed to prepare low-cost and high-quality graphene on a large scale through direct exfoliation of graphite in aqueous media using tannic acid (TA) as the stabilizer. The influence of preparation parameters on graphene concentration (CG) and graphite exfoliation efficiency (CG/CG,i), including TA concentration (CTA), initial graphite concentration (CG,i), pH, ionic strength, sonication time, and cycles, was systematically investigated. Under the optimum conditions, the highest CG that can be attained is 1.25 mg·mL–1 with CG/CG,i equal to 2.5%, and 92% of the as-formed graphene are few-layer graphene (below 5 layers) with the electrical conductivity as high as 488 S·cm–1. Due to TA on the graphene surface acting as the dual roles of dispersant and interfacial regulator, the high-quality graphene can be uniformly dispersed and tightly integrated into polymer matrices for high-performance and multifunctional polymer nanocomposites. In a word, this contribution provides a simple, green, high-efficiency, and scalable avenue for mass production and utilization of high-quality graphene.