Influence of picolinic acid on the electrochemical formation of silver nanostructures

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

Erlangen, Alemania

Congreso; 5th Kurt Schwabe Symposium in Electrochemistry; 2009

In recent years, the electrochemical metal deposition has been demonstrated like an approach for local surface nanostructuring through the formation of metal crystallites with nanometer-scale dimensions. Several groups have employed scanning probe microscopes to control the nano-particles nucleation and the active sites on the surface of the substrate [1-2]. Penner and co-workers have employed a multiple potentiostatic pulse method to obtain mesoscopic metal particles and wires by electrodeposition on HOPG surfaces [3-4]. These authors have found that it is possible to deduce a mechanism for the early stages of silver electrodeposition, depending on the selected experimental parameters at the potential programme to be applied. On the other side, it is well-known that organic additives can produce changes in the electrodeposition mechanism and in the physicochemical properties of the metallic deposit. It was found that picolinic acid produces modifications in the copper electrodeposition process as well as in the morphological structure of the deposit [5]. In this communication, the study of the first stages of silver crystallites electrochemical deposition on highly oriented pyrolytic graphite in the presence of picolinic acid (PA) was performed. Molecular aspect of the mechanism of the process was followed by in-situ SERS spectroscopy of PA during the growth of crystallites [6]. The electrodeposition of silver particles was carried out in aqueous KClO4 solutions at different pH values. Evidence of silver complex formation with the different PA species was observed in the voltammograms recorded under different conditions. The mechanism of silver nucleation and growth depends on the PA species which are present in the solution and the experimental parameters of the potential pulse programme used. The number of nuclei, the distribution on the surface and the size and form of the crystallites is modified when PA is present in the electrolyte. Chemical identification of the especies and the interaction between PA molecules and the deposited Ag crystallites is monitored by the changes produced in the SERS spectra related to the vibrational modes of PA. Morphology of Ag crystallites formed under different experimental conditions was observed by SEM.