An exploration on anti-corrosion performance of electrochemically synthesized graphene coating on commercially pure copper

Abstract

Graphene, a path-breaking discovery of the last decade has opened up numerous research avenues with its superior properties. Endowed with qualitative physical, electrical and optical characteristics, this “wonder material” has set the tone for many futuristic applications. The present work focuses on electrochemical exfoliation of graphite in sodium sulphate (Na2SO4) aqueous solution of 4 different molar concentrations to synthesize graphene. Graphite rods were subjected to pre-cathodic exfoliation in 1M H2SO4 solution after which anodic exfoliation was carried out in the aqueous solution at a potential of 10 V. The supernatant is disposed, the residue is washed thoroughly with acetone, and double distilled water. Subsequently, the collected material is dried and used for further characterizations. XRD and EDS analysis substantiate the presence of graphene nano-sheets along with traces of oxygen. Raman studies pointed out that the graphene synthesized at lower molar concentration had less defects owing to slow and smooth exfoliation. UV studies point out to electronic transitions in C=C bonds present in the graphene sheets. Graphene with few layered structures and stacked onto one another, were obtained for all concentrations in SEM. Transparent, curled layers are depicted through TEM morphologies. FTIR shows minimum oxygenation occurring at lower molarities. Graphene nano-sheets are coated onto copper substrates via electrophoretic deposition at a constant voltage of 5 V and different timings. The coated samples are then made to undergo corrosion tests in 3.5 wt% NaCl solution. Graphene coatings prove effective in combating corrosion and it is worth noting that bi-layer coatings prove to be more efficient in comparison to single or multi-layer coatings.