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 (C_G) and graphite exfoliation efficiency (C_G/C_G,i), including TA concentration (C_TA), initial graphite concentration (C_G,i), pH, ionic strength, sonication time, and cycles, was systematically investigated. Under the optimum conditions, the highest C_G that can be attained is 1.25 mg·mL^–1 with C_G/C_G,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