Electrochemical evidence of caffeine adsorption on zinc surface in ethanol

Several electrochemical methods were employed to confirm the ability of caffeine (1,3,7-trimethylxanthine) to adsorb on zinc surface in aerated ethanol solutions. The interaction between the organic compound and the electrode surface was dependent on the electrode potential. Adsorption on the electrode surface was confirmed by comparing the voltammograms, Tafel plots and EIS curves of a zinc electrode in the absence and presence of dissolved caffeine. The calculated standard free energy of adsorption confirms a spontaneous chemical adsorption step.