Synthesis of graphene via electrochemical exfoliation in different electrolytes for direct electrodeposition of a Cu/graphene composite coating.

Directly dispersing graphene into an electrolyte still remains a crucial difficulty in electrodepositing a graphene enhanced composite coating onto electrical contact materials. Herein, graphene was synthesized via electrochemical exfoliation in an N,N-dimethylformamide (DMF)/H2O solution containing (NH4)2SO4. The electrochemically exfoliated graphene nanosheets (GNs) were directly dispersed by sonication. In comparison with graphene synthesized from aqueous solution, the GNs electrochemically exfoliated in the DMF/H2O-(NH4)2SO4 solution exhibit a lower degree of oxidation. Cu/graphene composite coatings were subsequently electrodeposited onto Cu foils by adding Cu2+ into the as-fabricated graphene solution. The surface nanostructure of the Cu/graphene composite coatings was transformed from loose pine needles to a uniform and compact structure with an increase in the concentration of Cu2+, which indicated that the controllable synthesis of Cu/graphene composite coatings with different performances could be achieved in graphene dispersions after adding Cu2+. In order to synthesize graphene via electrochemical exfoliation and directly electrodeposit a Cu/graphene composite coating without adding CuSO4 or any other additive, an attempt was made to directly electrodeposit a Cu/graphene composite coating in CuSO4/DMF/H2O solution after electrochemical exfoliation.