Efecto Electrocatalítico de nanopartículas bimetálicas de Ag y Cd hacia la reducción de iones nitrato y/o nitrito

SILVANA G. GARCÍA; RUBÉN E. AMBRUSI

Cordoba

Congreso; Congreso Internacional de Metalurgia y Materiales- 16° SAM-CONAMET; 2016

In the present work,the electrocatalytic effect of Cd-Ag bimetallic nanoparticles supported on highly oriented pyrolytic graphite (HOPG) and vitreous carbon (VC) substrates was evaluated , for the reduction of nitrate and/or nitrite ions, processes involving different electrochemical reactions [1]. Initially, the electrochemical technique of the single potentiostatic pulse was used in order to obtain the metallic and bimetallic deposits on the carbonaceous substrates. Moreover, in the later case, the amount of Cd selectively deposited on the Ag nanoparticles supported on HOPG or CV, was varied using different polarization times. On the other hand, potentiodynamic studies were carried out employing HOPG and VC modified electrodes with Ag, Cd, and Ag-Cd nanoparticles, which indicated that, for relatively large polarization times, it is feasible the formation of Ag and Cd surface alloys [2]. The generated particles were characterized by exsitu AFM and XPS analysis, corroborating the latter the formation of a Cd-Ag alloy. Subsequently, the electrodesmodified with metallic and bimetallic nanoparticles, and also the substrates free of deposits, were analysed by cyclic voltammetry in solutions containing nitrate ions. This procedure allowed to associate the presence of cathodic current peaks with the reduction of nitrate and/or nitrite ions. Also, it was found that these processes begin at more positive potential values in the case of bimetallic deposits, corresponding to a more pronounced catalytic effect by the presence of Cd and Ag, which could be alloyed in the surface, producing a synergistic effect for the reduction of the anions. Inclusive, it was verified a change in the catalytic performance by using longer polarization times for the deposition of Cd on supported Ag nanoparticles, that could be related with the alloy formation between these metals. The reaction products were analyzed by colorimetry and ion exchange chromatography determining nitrate, nitrite and ammonium amounts in solution.REFERENCIAS1. M. Paidar, I. Rousar, K. Bouzek, ?Electrochemical removal of nitrate ions in waste solutions after regeneration of ion exchange columns?, J. Appl. Electrochem., Vol. 29 (1999), p. 611-617.2. R.E. Ambrusi, G. Staikov, S.G. García,? Electrochemical synthesis of Cd-Ag bimetallic particles and the involved alloy formation?, J. Electroanalytical Chemistry, Vol. 728 (2014), p. 272-276.