ON THE LIMITS OF UNDERPOTENTIAL DEPOSITION IN THE NANOSCALE.

O A. OVIEDO, O. A. PINTO, L. REINAUDI AND E. P. M. LEIVA.

Congreso; 64 annual meeting of the International Society of Electrochemistry; 2013

Nanoelectrochemistry appears as a promising field where researchers have been able to generate and control structures at atomic and molecular level in order to obtain surfaces and structures with novel properties. The main advantage of these types of methods is the precise control that can be achieved in conditions of under/oversaturation of the interface. Electrochemical techniques that were initially developed for the modification of surfaces, are now successfully applied in systems with high rates of curvature [1,2]. A widely used method for the controlled modification of nanoparticles is underpotential deposition, commonly called upd, in contrast with overpotential deposition (opd). This type of control method allows even allows to achieve fractions of a monolayer [3]. Given the large curvature effects at the nanoscale, the upd process presents significant deviations from metal deposition at flat surfaces. For example, an upd-opd transition has been predicted with increasing nanoparticle size [1-4]. Computer simulations have shown that in the case of a Au nanoparticle decorated with Ag or Pd, the upd-opd transition occurs at about 4 nm and 5 nm in diameter, respectively. While many aspects of the electrodeposition processes mentioned above can be explained, others remain yet to be understood, leaving a fruitful field for theoretical and computational modeling. In the present work, we present a phenomenological equation that allows determination of the upd-opd transition for different metallic nanoparticles at the nanoscale. Computer simulations are used to demonstrate the main features of the modeling. This work is relevant for the control of size and shape of nanoparticles, using upd to block (or to favor) growth at the nanoscale [5].