r-GO/oil barrier coating protects metal against corrosion. (a) Schematic drawing illustrating a 3-electrode electrochemical setup to evaluate the r-GO/oil film’s anticorrosion performance in 1 M (3%) HCl. (b) Potentiodynamic polarization curves of uncoated (purple line) and coated (red line) Al wires, showing that the r-GO/oil film indeed acts as a barrier and prevents the underlying Al from reacting with HCl. (c) An Al wire (1.02 mm diameter) is severely etched after just one hour in concentrated HCl 5.5 M or 17% HCl. (d) In contrast, an Al wire coated with r-GO/oil film remains intact after at least 3 months.