Graphene Wet-etching Kinetics as Time-reversed Crystallization

Wet-etching kinetics of single-layer graphene and multilayer graphene oxide by piranha solution under a mild condition was modeled as a time-reversed crystallization process and was analyzed by Avrami theory. The Avrami exponent is 1 at the early stage of the reaction for both materials, indicating that etching proceeds along reactive edges without forming additional defects. Then, the exponent for graphene changes to 2 whereas that of graphene oxide increases to 4. Stretched exponential behavior is also observed for highly defective samples.