Exfoliation of graphite to turbostratic graphene

Abstract

Here, we exfoliated high-quality turbostratic graphene with a clean interface at a high production rate (10 g/h) directly from graphite using an industrial-friendly technique i.e., plasma spraying, catching note of its growing global interest. The reduction of the (002) X-ray diffraction peak and the transparent scanning electron microscope (SEM) image are used to characterize the exfoliation. The thickness of exfoliated graphene layers is measured using an atomic force microscope (AFM). Turbostratic nature (twist) in graphene is identified based on the appearance of three Raman combination bands (TS1, TS2, and TS3) between 1800 cm-1 and 2300 cm-1. The twist between the layers is precisely measured using selected area electron diffraction (SAED), and the turbostratic nature is confirmed by observing a moiré pattern utilizing a high-resolution transmission electron microscope (HR-TEM). The produced turbostratic graphene exhibited large variability in twist angles (2⁰-30⁰) with a visible moiré pattern. The high crystalline quality and clean interface between single layers of graphene were confirmed by the moiré pattern and SAED. Later, we demonstrated the mechanism underlying the twist in our exfoliated graphene, which could open the way for the production of high-quality turbostratic graphene with clean interfaces.