Evidence of caffeine adsorption on a low-carbon steel surface in ethanol

Different electrochemical methods have been employed in order to confirm the ability of caffeine (1,3,7-trimethylxanthine) to adsorb to low-carbon steel in ethanol solutions and thereby inhibit the corrosion process. The interaction between the organic compound and the electrode surface was dependent on the electrode potential and the maximum interaction was observed at −0.30 V (Ag/AgCl). The presence of the organic compound adsorbed on a low-carbon steel electrode surface was confirmed by comparing the voltammograms, Tafel plots and EIS curves of the electrode in the absence and presence of caffeine. The standard free energy of adsorption confirms a spontaneous chemical adsorption step.