Surface Chemistry of Gold Nanoparticles Produced by Laser Ablation in Aqueous Media

The femtosecond laser ablation of a gold target in aqueous solutions has been used to produce colloidal Au nanoparticles with controlled surface chemistry. A detailed chemical analysis showed that the nanoparticles formed were partially oxidized by the oxygen present in solution. The hydroxylation of these Au−O compounds, followed by a proton loss to give surface Au−O-, resulted in the negative charging of the nanoparticles. The partial oxidation of the gold nanoparticle surface enhances its chemical reactivity and consequently has a strong impact on its growth. In particular, the oxidized surface reacted efficiently with Cl- and OH- to augment its net surface charge. This limited the coalescence of the…