INVESTIGADORES
AMBRUSI Ruben Eduardo
congresos y reuniones científicas
Título:
Electrochemical Formation of Ag-Cd Nanowires onto HOPG
Autor/es:
RUBÉN E. AMBRUSI, SILVANA G. GARCÍA, DANIEL R. SALINAS
Lugar:
Nice
Reunión:
Congreso; The 61st Annual Meeting of the International Society of Electrochemistry; 2010
Resumen:
The development of metallic nanowires has attracted much attention in recent yearsbecause of the interesting chemical, physical and mechanical properties of thesestructures, as well as, for their potential applications in nanotechnology. One of themethods that have been used for their preparation is the electrochemical deposition [1].In this case two procedures were followed: a) the use of porous masks, by depositingthe metal into the pores; b) by preferential electrochemical deposition of the metal onthe step edges of the highly oriented pyrolytic graphite (HOPG) surface [2].In the present work, the formation of Ag-Cd bimetallic nanowires onto the HOPGsurface was studied by applying, initially, the triple potentiostatic step technique in asolution containing 5 mM Ag2SO4 + 0,1 M H2SO4. The first potential step was appliedto the HOPG substrate, using a potential value positive enough to activate the surfacestep edges. The subsequent cathodic potential steps allowed the selective nucleationand growth of Ag nanocrystals at the pre-activated step edges. The characterization ofthe formed deposits (nanocrystals or nanowires, depending on the polarizationconditions used) was performed using atomic force microscopy (AFM) and scanningelectron microscopy (SEM), determining the preferential sites of nucleation andgrowth, the size of crystallites and the thickness and continuity of the obtainednanowires.Afterwards, potentiostatic and potentiodynamic experiments were performed in 5 mMCdSO4 + 5 mM H2SO4 + 0,5 M Na2SO4 solution using the HOPG/(Ag nanowires)modified substrate. The underpotential deposition process of Cd on Ag is well known[3,4], therefore, the selective deposition of Cd onto the Ag nanowires present on thesurface could be obtained by adjusting the polarization conditions used. The formationof a Ag-Cd ?core-shell? structure or an alloy during this process were also considered.