Density functional theory study on the reaction mechanism of reductants for electroless Ag deposition process

Oxidation reaction mechanisms of reductants for electroless Ag deposition process were investigated using density functional theory calculation, focusing upon behavior of the reaction intermediate species. It was indicated that the oxidation processes of reductants, such as dimethylamine borane, formaldehyde, and hypophosphite ion, on the Ag surface are initiated by addition of OH- and proceed via five-coordinate intermediate species. Catalytic activity of the Ag surface for the oxidation reaction of the reductants was investigated by using energy density analysis, focusing upon the local interaction of the species. The results indicated that the adsorption of the reductants onto the Ag surface is driven by destabilization of the reductant and stabilization of the Ag surface. It was also indicated that the destabilization of the five-coordinate intermediate species at the Ag surface is a key factor of the "catalytic activity" for the oxidation reaction. In the case of the reaction of formaldehyde, in which the Ag surface acts as catalyst, the intermediates were considerably activated at the Ag surface, whereas such an effect was not clearly seen with the hypophosphite ion, for which the Ag surface is not catalytic. It was also suggested that the activation of the intermediates is affected by coordination behavior of OH- species. (c) 2007 The Electrochemical Society.