Effect of Solvent Isotopic Replacement on the Structure Evolution of Gold Nanorods

We report the effect of solvent isotopic replacement on the structure evolution of gold nanorods synthesized in aqueous solution using the Ag(I)-mediated seeded-growth method (see Nikoobakht, B.; El-Sayed, M. A. Chem. Mater. 2003, 15, 1957). With increasing replacement of water by deuterium oxide, both higher yields and aspect ratios are observed. With increasing reaction time the variance of particle anisotropy is found to decrease in deuterium oxide and increase in regular aqueous solution. The effect is interpreted as a consequence of the reduced solubility of the surfactant and metal salts that extends a complex and multifaceted effect on the reaction process, including mass transport and chemical potential, but also on surface reconstruction processes that have been related to the shape evolution in gold nanorod solutions. The increase in efficiency of the seeded-growth process in D 2 O solution furthermore is shown to facilitate the reduction of the surfactant concentration during particle synthesis by an order of magnitude as compared to regular aqueous solution.