Spectroelectrochemical study of picolinic acid adsorption during silver electrodeposition

CECILIA I. VÁZQUEZ; GUSTAVO F. S. ANDRADE; MARCIA L. A. TEMPERINI; GABRIELA I. LACCONI

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 156 p. 154 - 162

0013-4686

The adsorption of picolinic acid (PA) onto HOPG electrodes during silver electrodeposition at pH 3.0 was examined using conventional electrochemical techniques: cyclic voltammetry and impedance measure- ments (differential capacity-potential plots) and Surface-Enhanced Raman Spectroscopy (SERS), through a wide range of electrode potentials. The spectroelectrochemical results indicate that the electroactive species for silver electrodeposition are Ag+ ions and [Ag(Pic)] complexes, in spite of the predominant species in solution being the zwitterion (HPic). Adsorption of the anion (Pic?) occurs through a wide potential range where the electrode surface charge density is positive. However, HPic deprotonation, hydrogen formation and Pic? desorption, with the consequent decrease in SERS intensity, occur at the zero-charge potential (pzc) for HOPG.