Graphene oxide with dopamine functionalization as corrosion inhibitor against sweet corrosion of X60 carbon steel under static and hydrodynamic flow systems

Under static and hydrodynamic conditions, a graphene oxide with dopamine functionalization (DA-GO) was employed as a corrosion inhibitor for X60 carbon steel in a CO₂-saturated 3.5 % NaCl solution. Electrochemical methods were combined with surface analytical techniques to assess the inhibitor's performance. At 2 ppm, DA-GO exhibited a high inhibition efficiency of over 90 % according to the results from the potentiodynamic polarization technique. The addition of the inhibitor resulted in an increase in charge transfer resistance at the steel/solution interface. Polarization experiments revealed that DA-GO acts primarily as a mixed-type inhibitor under the static condition and as a cathodic-type inhibitor under the hydrodynamic condition. Adsorption of DA-GO on the steel substrate followed the Langmuir adsorption isotherm, suggesting a combination of physical and chemical adsorption mechanisms. The inhibitor adsorption on the steel substrate was confirmed by surface characterization using SEM, AFM, and XPS techniques.