A chemometric investigation on the influence of the nature and concentration of supporting electrolyte on charging currents in electrochemistry

Abstract In electrochemical experiments, supporting electrolyte is used to confine the differences of potential to a narrow region close to the electrode, to reduce the migration of the analyte and to decrease the resistance of the solution. However, since usually high concentration of supporting electrolyte is used, it can interfere with electrochemical analysis, and hence its effect should be considered. Besides that, each ion carries a special charge and has different nature, so their effect on the electrochemical system is different, and analysis of their effect is hard to be understood using traditional methods. One electrochemical parameter, which can be affected by the nature and concentration of supporting electrolytes is contribution of charging currents in total electrochemical current passing the electrochemical cell. In continuation of our work on resolving different types of currents, here multivariate curve resolution alternative least squares as a powerful chemometric technique was used for current deconvolution in the presence of different types of supporting electrolytes including KCl, NaCl, KF, NaF, KBr, NaBr, KOH, NaOH, KNO3 and NaNO3. Based on the obtained results, sodium-containing salts are preferred because in their presence higher contribution of faradaic current was obtained. In addition, results showed that increasing concentration of supporting electrolyte causes to decrease faradaic current contribution.