Smoothening Mechanism of Thiourea on Silver Electrodeposition : Real Time Imaging of the Growth Front Evolution

• Autores: Azzaroni, Omar; Schilardi, Patricia Laura; Salvarezza, Roberto Carlos; Arvia, Alejandro Jorge
• Año de publicación: 1999
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas; Química; Interfaces; Crystallization; Diffusion; Ions; Electrodeposition
• Institución: Universidad Nacional de La Plata

Ag electrodeposits were grown on a polycrystalline Ag cathode at either 0.01 or 1 mA cm^-2 from aqueous 5 × 10^-3 M Ag₂SO₄ + 10^-2 M H₂SO₄ + 0.5 M Na₂SO₄, in the absence and presence of different amounts of thiourea (TU). The cathode/solution interface evolution in a quasi-bidimensional electrochemical cell was followed with a video microscope imaging system. From TU-free solution a nodular morphology at 0.01 mA cm^-2 and a branched morphology at 1 mA cm^-2 were observed. At 0.01 mA cm^-2 the presence of TU drove the interface motion to a stable roughness regime by suppressing the nucleation and growth of instabilities. Accordingly, the characteristics of the growth front were consistent with the predictions of the Edwards−Wilkinson equation for the interface motion. At 1 mA cm^-2, those electrodeposits grown in the presence of TU showed a decrease in both the nucleation and growth rates of instabilities, although they were not fully suppressed.
Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas