Field emission from cylindrical graphene cathodes prepared by chemical vapor deposition and cold rolling

We report field emission (FE) properties of cold cathodes made by a scalable chemical vapor deposition synthesis of three-dimensional graphene (3DG) from a cast catalyst followed by cold rolling. This process leads to an increase in mechanical strength and electrical conductivity of the tested material. For a given distance between the tip of the cathode and the anode, it is found that the FE current from the edge of a single sheet of cold-rolled 3DG-based cathode can be increased by over one order of magnitude when rolling the 3DG sheet in the shape of a cylinder with several turns. A FE current in the order of 4.5 mA was measured from a 3 mm diameter cold-rolled 3DG cylinder with six turns at a bias of 2400 V for a separation of 0.5 mm between the tip of the cylindrical cathode and the anode. The FE data of all cold-rolled 3DG-based cathodes are well fitted by the expression proposed by Abbot, Henderson, Forbes, and Popov [Filippov et al., R. Soc. Open Sci. 9, 220748 (2022)], Im=CVmκexp(−B/Vm), where Im is the FE current, Vm is the bias applied between the cathode and anode, and B and C are fitting parameters. It is found that κ=1 and 3/2 for FE from the surface and edge of the cold-rolled based cathodes, respectively.