Electrochemical deposition of Te adlayers onto 3D networks of gold nanoparticles

The controlled electrochemical deposition of atomic layers of Te onto 3D assemblies of Au nanoparticles in acid solution is reported for the first time. Citrated stabilized Au particles of 19.3 ± 1.2 nm diameter were assembled into two- and three-dimensional networks via electrostatic layer-by-layer adsorption employing poly-l-lysine (PLL) on In-doped SnO2 (ITO) electrodes. Atomic force microscopy (AFM) and electrochemical measurements showed that the 3D assemblies consist of an open network of electrically interconnected nanoparticles. Electrochemical studies in the presence of TeO2 show two distinct features associated with one and two atomic adlayers of Te selectively deposited onto the Au nanocrystals. Detailed analysis of the electrochemical responses as a function of the surface corrugation showed that the average Te coverage on a single Au nanoparticle is close to those observed on extended Au surfaces. The results demonstrate that the surface composition of each individual particle in the 3D assembly can be electrochemically modified at the atomic level. The implications of these findings for the design of electrocatalytically active ultrathin composites are briefly discussed.