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.