Measurements of the Potentials of Zero Free Charge and Zero Total Charge for 1-thio- ± bβ-D-glucose and DPTL Modified Au(111) Surface in Different Electrolyte Solutions

Abstract

Abstract The immersion method was used to measure the potential of zero free charge (E pzfc) of a bare Au(111) electrode and the electrode modified by self-assembled monolayers (SAMs) of 1-thio-β-D-glucose (β-Tg) and 2,3-di-O-phytanyl-sn-glycerol-1-tetraethylene glycol-D,L-α-lipoic acid ester (DPTL). The measurements were performed in three electrolyte solutions: 0.1 M NaH2PO4, 0.1 MKClO4 and 0.1 M NaF. The E pzc of the Au(111) electrode has different values in these electrolyte solutions due to the specific adsorption of phosphate and fluoride anions on the Au(111) surface. In contrast, when the gold surface is covered by a SAM of β-Tg, the adsorption of anions is suppressed and similar values of E pzfc were measured in the three electrolytes. Additional chronocoulometric experiments were performed to determine the potentials of the zero total charge (E pztc) for the thiol covered electrode. Significant differences between numerical values of potentials of the zero free charge E pzfc and potentials of the zero total charge E pztc were observed.