Transition metal catalysts coordinated with electrochemistry for preparation of graphene

It is still crucial to produce mass high-quality graphene through simple and low-cost methods for its wide applications. Herein, a simple and fast method by combining inexpensive transition metal catalysts with electrochemistry to exfoliate natural flake graphite is reported. The electrode is prepared in a sandwich structure, where the titanium mesh will enwrap the nickel net coated with graphite powder. This method can quickly achieve the large-scale preparation of graphene within 15 min. The quality of graphene with large lateral size and few layers has been characterized by XRD, SEM, TEM, Raman, and AFM. The possible electrochemical exfoliation mechanism has been proposed. Oxygen evolution reaction occurs at the anode due to the transition metal catalysts, and hydrogen ions (H+) are generated along with oxygen, H+ and SO42− ions will form a local strong acid. The formation of strong acidic H2SO4 in-situ around electrode will oxidize the edge of the graphite, allowing the intercalation of SO42−, H2O, SO2 and O2 into the graphite sheets, which will inflate the graphite and exfoliate of graphite into graphene. This strategy is reliable, environmentally friendly, and suitable for industrial production.