Long-Lifespan Turbostratic Graphene Field Emitters for High-Power Applications.

Cold cathodes offer heater-free, instantly switchable electron sources, but conventional sharp-tip designs often degrade under continuous thermal loads, limiting high-power applications. We overcome this with a freestanding, edge-emitting turbostratic graphene film (GF). Its turbostratic stacked layers are assembled via solution-phase pre-gelation of graphene oxide, followed by thermal restoration and densification. A 300 nm-thick, 1 cm-wide GF emission edge can sustain 1.5 mA (52 A cm-2) DC current for 588 h, with an exceptionally low degradation rate below 0.042% h-1. This durability is an order of magnitude better than previous carbon cathodes at similar current densities. This performance meets critical requirements for modern high-power vacuum electron applications. Our cost-effective, scalable architecture bridges nanoscopic field enhancement with macroscopic heat management, significantly broadening cold cathode applications.