Macroscopic, freestanding, and tubular graphene architectures fabricated via thermal annealing

Manipulation of individual graphene sheets/films into specific architectures at macroscopic scales is crucially important for practical uses of graphene. We present herein a versatile and robust method based on annealing of solid carbon precursors on nickel templates and thermo-Assisted removal of poly(methyl methacrylate) under low vacuum of ∼0.6 Pa for fabrication of macroscopic, freestanding, and tubular graphene (TG) architectures. Specifically, the TG architectures can be obtained as individual and woven tubes with a diameter of ∼50 μm, a wall thickness in the range of 2.1-2.9 nm, a density of ∼1.53 mg·cm^-3, a thermal stability up to 600 °C in air, an electrical conductivity of ∼1.48 × 10⁶ S·m^-1, and field emission current densities on the order of 10⁴ A·cm^-2 at low applied electrical fields of 0.6-0.7 V·μm^-1. These properties show great promise for applications in flexible and lightweight electronics, electron guns, or X-ray tube sources.