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High-quality reduced graphene oxide (rGO) sheets can be accessible through Langmuir-Blodgett self-assembly (LBSA) on copper foil and dielectric substrate under high temperature ethanol vapors via chemical vapor deposition (CVD) process. Through the LBSA forming method, a uniform and smooth graphene oxide (GO) film can be obtained on the target substrate, which is more economical and efficient compared to the traditional growth strategy. Moreover, the GO-derived graphene film repaired on copper was nearly defect-free with a negligible defect density (ID/IG ratio of 2/Si, 0.2 kΩ/sq prepared on copper and subsequently transferred to SiO2/Si) that had surpassed other GO-derived graphene ever reported. Meanwhile, we demonstrate that Cu-vapor will degrade the restoration efficiency when introduced remotely, which is quite different from previous studies on graphene growth.

Reduced graphene oxide bundles with sharp tips were fabricated by a simple approach with freeze-drying and hydrothermal reduction, and this approach could modify the surface topography of the field emission cathode and make more graphene bundles sharpen and aligned. This field emission cathode material displayed excellent field emission properties decreased from 2.9 V μm−1 to a low turn-on field of 0.8 V μm−1 at the emission current density of 10 μA cm−2. Sharp graphene emitter arrays have sharp protruded tips in abundance, leading to an enlarged field enhancement factor from 1683 to 10182, which was much better than those films prepared by other methods we adopted. It also revealed a good field emission stability with no degradation in the current for 3 h. We believe that this approach can enhance the field emission performance of graphene emitters, which could be widely candidate for various field emission applications.