▎ 摘　　要

To optimize the field emission behavior of graphene, a simple, low-cost and large-scale method was developed to introduce metallic particles onto the graphene and is described in the present report. Cu/graphene composite field emitters were fabricated by the one-step process of electrophoretic deposition. The Cu/graphene composite emitters prepared with this technique showed a lower turn-on electrode of 1.55 V/mu m, lower threshold field of 2.45 V/mu m and higher field enhancement factor of 5600 compared with those of the pristine graphene. The optimized field emission properties of the Cu/graphene composite were mainly attributed to the introduced Cu nanoparticles, which increased the density of the emission sites and decreased the series resistance. These results provide us with a new approach to optimize graphene-based emitters for vacuum devices.