Underpotential Deposition of Copper onto 3D Gold Nanostructures

The electrochemical formation of atomic adlayers introduces significant changes in the electrocatalytic properties of electrode surfaces. In the present contribution, we study the surface properties of Au nanoparticles analysing the electrochemical responses associated to the copper underpotential deposition (upd) in acid pH. The Au nanoparticles were synthesised by the chemical method, using HAuCl₄ and trisodium citrate with an average diameter of 19.2 ± 1.2 nm. Three-dimensional networks of Au nanoparticles were assembled via electrostatic layer-by-layer adsorption employing poly-L-Lysine (PLL) on In-doped SnO₂ electrodes (ITO). The electrochemical studies in sulfuric acid (Figure 1A) show the voltammetry behavior, while (Figure 1B) in copper sulfate (CuSO₄) show the potentiostatic current transients of Cu onto Au nanoparticles. Detailed electrochemical analysis of the responses showed that the average Cu coverage on a single Au nanoparticle is close to those observed at extended Au surfaces. These results demonstrate that each individual nanoparticle in the assembly participate in the electrochemical copper deposition.