Synthesis of l-Histidine-Attached Graphene Nanomaterials and Their Application for Steel Protection

Graphene-based carbonaceous materials have aroused great attention among the material protection fields due to their excellent impermeability. However, graphene nanosheets tend to aggregate in a polymer matrix and trigger microgalvanic corrosion, which potentially aggravates metal deterioration. Herein, we present a facile strategy to improve the protective property of graphene by tailoring graphene oxide with l-histidine molecules. The resultant functionalized graphene nanomaterials, without direct connections, can be well-dispersed in a polymer matrix. Electrochemical impedance measurements demonstrated that embedding a small percentage of well-dispersed functionalized graphene in epoxy coatings significantly enhanced the impermeable properties of the as-prepared composite coatings. The probability of galvanic corrosion of graphene with metal was largely inhibited and verified through the scanning vibrating electrode technique. The protection mechanism of composite coatings is interpreted as the barrier property of graphene nanosheets by suppressing the diffusion of corrosive species and the isolate function of l-histidine at the edge of graphene lamellae via increasing the electrical resistance.