Suppression of secondary electron emission of oxygen free copper by two-step electrodeposition of rGO/Cu composite coating

We prepared a reduced-graphene-oxide/Cu (rGO/Cu) composite coating to suppress the total secondary electron yield by two-step electrodeposition. We found that driven by the applied electric field, copper ions can enter the interior of graphene oxide (GO) film and nucleate, while the surface is still GO. The rGO/Cu composite coating was obtained by heat treatment with a combination of hydrogen and argon. After heat treatment, XPS analysis shows that the oxygen content of rGO on the surface of the composite coating is reduced from 31.29 at.% to 11.00 at.%, and the carbon content is 85.25 at.%. Raman analysis shows that rGO is still mainly sp2 hybrid structure. The deposited copper particles sintered in the composite coating and formed Cu-O-C chemical bond. The maximum secondary electron yield (δmax) is 1.10, which is close to the δmax of rGO coating (1.09). Compared with the rGO coating, the presence of copper in the rGO/Cu composite coating slightly increases the TEY, but significantly improves the bonding strength between the coating and the substrate at high temperatures.