A Novel Electrochemical Strategy for the Production of Bimetallic Nanoparticles

M. FONTICELLI; G. CORTHEY; C. VERICAT; G. BENITEZ; L. GIOVANETTI; F. REQUEJO; S. SHON; R. C. SALVAREZZA

, Foz do Iguacu, 16 al 19 de marzo de 2008

Congreso; 6th Spring Meeting of the International Society of Electrochemistry; 2008

International Society of Electrochemistry

Bimetallic Nanoparticles (BNPs) have attracted much attention because of the size dependent tuning of their electrical, optical and catalytic properties. In fact, bimetallic Ag-AuNPs have been used to transform poisonous carbon monoxide into less-harmful carbon dioxide at room temperature[1]. Furthermore, Pd-AuNPs are the most effective catalysts yet identified for remediation of groundwater pollutants such as trichloroethene[2]. As BNPs are becoming very important materials (both, in sensors and in water, atmospheric and soil catalytic remediation), the need for developing more environmentally friendly and sustainable methods for their synthesis is evident. While methods for BNPs synthesis based on wet chemistry occur far from equilibrium, some electrochemical strategies are carried out under thermodynamic control (e.g. Underpotential Deposition (UPD), and ECALE). The least implications of the intrinsic characteristics that each methodology have, are some scaling up difficulties for the wet chemical methods, whereas the electrochemical ones would be limited to conducting substrates. We describe a currentless method based on solution chemistry in order to prepare Ag-AuNPs. This method use the combination of two well established electrochemical facts: the UPD phenomena and the ability of a redox couple to control the interfacial potential. We have selected the Ag‑Au surfaces because they can be taken as a model of bimetallic systems. In general, solution metal cations can be deposited by controlling the interfacial potential. Beside this strategy is commonly used in electroless processes, in our case the potential was carefully fixed in the UPD range in order to work under equilibrium conditions. At these circumstances, bimetallic surfaces can be easily prepared by a simple solution chemistry process[3]. Our results are also discussed in relation with the requirements of a green chemistry approach (e.g. water soluble reactive and products; environmental friendly reducing agents[4]). [1] (a) Liu, et. al. J. Phys. Chem. B. 2005, 109, 40. (b) Wang, et. al. J. Phys. Chem. B., 2005, 109, 18860. [2] , M. O.; Hughes, J. B.; Wong, M. Environ. Sci. Technol. 2005, 39, 1346. [3] Fonticelli, et. al. J. Phys. Chem. C., 2007, 111, 9359. [4] Raveendran, P.; Fu, J.; Wallen, S. L., Green Chem., 2006, 8, 34–38.