Bulk graphene/multi-walled carbon nanotubes based field emitters

Graphene and carbon nanotubes are excellent field emission materials. However, film-based emitters were easily damaged with poor long-time stability. Here, for the first time, we developed the bulk graphene/carbon nanotubes hybrid materials for field emission applications. The bulk material was synthesized by a quick and easy method of cold-pressing. The effects of pressure and the carbon nanotubes content on the field emission performance were quantitatively studied. The novel bulk emitters exhibited an excellent field emission performance achieving the maximum current density of 364.47 mA/cm2 at 3.73 V/μm. Besides, a stable emission of 219.34 mA/cm2 was obtained continuously for over 36 h. Hence, the bulk emitters can be used in high-power cold cathode applications, such as 3D printing, electron beam welding and electron beam melting.