Metal nanoparticles and H2 induced etching of graphene are of significant interest to synthesise graphene nanoribbons and various other structures with crystallographically defined edges. Here, we demonstrate a controllable H2-induced etching process of graphene crystals to fabricate nanoribbons, and Y-junction structures with pronounced edges. Individual graphene crystals and continuous films were grown on Cu foil by the solid source chemical vapor deposition (CVD) technique. The etching behavior of the synthesized graphene was investigated by annealing at 1000 °C in a gas mixture of H2 and Ar. A highly anisotropic etching creates hexagonal holes, nanoribbons and Y-junction graphene with clear edge structures. The distinct graphene edges of individual ribbons create a 120° angle to form a Y-shaped structure. The finding may be significant for fabricating well-defined graphene structures with controlled edges for electronic device applications as well as creating in-plane heterostructures with other two dimensional (2D) materials
