LACCONI Gabriela Ines
congresos y reuniones científicas
In-situ monitoring of silver electrodeposition by SERS spectroscopy (Exposición oral)
New London, NH, Estados Unidos
Conferencia; Gordon Research Conference on Electrodeposition; 2010
Institución organizadora:
Gordon Research Conference
In-situ monitoring of silver electrodeposition by SERS spectroscopy C.I. Vázquez1, G. F.Andrade2, M. L. A. Temperini2, G.I. Lacconi1* 1INFIQC, Dto. Fisicoquímica, Facultad Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina. 2Instituto de Química, Universidade de São Paulo, São Paulo, Brazil. *E-mail: In recent years, the pronounced optical properties of noble metals nanoparticles have been widely investigated and applied to studying the surface-enhanced Raman scattering (SERS) phenomena [1]. SERS occurring on nanoscale colloids and metal-island films, especially on silver, gold and copper, provides a powerful tool for the adquisition of vibrational information on adsorbate?surface interactions in view of its unique sensitivity and excellent frequency resolution [2]. The electrochemical synthesis of the metallic nanoparticles involves the application of a potentiostatic multiple pulse program that make possible a tune of the size, form and dispersion control [3]. By combining electrochemical programs for silver nucleation and growth with the organic additives adsorption effect, a new SERS active Ag clusters-HOPG (highly oriented pyrolytic graphite) substrate is obtained. Also, it is well-known that organic additives, such as pyridine-carboxylic acids, produce changes in the nucleation mechanism, modifying the physicochemical and morphological properties of the deposits [4, 5]. In this communication, the study of first stages of silver electrodeposition onto HOPG in the presence of picolinic acid (PA) is performed. Molecular aspect of the mechanism of the process was followed by in-situ SERS spectroscopy of PA during the growth of crystallites [6]. Electroformation of silver crystallites was carried out in aqueous KClO4 solutions containing different concentrations of PA, at various pH values. Evidence of silver complex formation with the different PA species was observed in the j/E potentiodynamic profiles. The mechanism of silver nucleation and growth depends on the PA species present in the solution and the experimental parameters of the potential pulse programme used. The number of nuclei, their distribution on the surface and the size and form of the crystallites can be modified by the presence of PA species in the electrolyte. Very high quality SER spectra directly associated with the electrochemical behaviour enabled extensive study of the spectral variation with experimental conditions, such us the bulk pH, additive concentration and electrode potential. Chemical identification of the species and the interaction between PA molecules and the deposited Ag crystallites were monitored by the changes produced in the SERS spectra related to the vibrational modes of PA. 1- Plieth, W., Dietz, H., Anders, A., Sandmann, G., Meixner, A., Weber, M., Kneppe, H.; Surf. Science 597 (2005) 119. 2- Kolb, D.M.; Engelmann, G.E.; Ziegler, J.C.; Solid State Ionics 131 (2000) 69. 3- Penner, R.M.; J. Phys. Chem. B 106 (2002) 3339. 4- D.H. Dressler, Y. Mastai, M. Rosenbluh, Y. Fleger; J. Molec. Struct. 935 (2009) 92. 5- Portela, A.L.; M. López Teijelo; Lacconi, G.I.; Electrochim. Acta 51 (2006) 3261. 6- Wen, R.; Fang, Y.; Vibr. Spectrosc. 39 (2005) 106.