Monodisperse, quasi-spherical silver nanocrystals (Ag NCs) have been produced directly in water via adding the aqueous solution of a mixture of AgNO3, sodium citrate, and KI into the boiling aqueous solutions of ascorbic acid (AA). The AA is used to significantly accelerate reduction of AgNO3 in order to promote a very fast nucleation, and the KI is used to tailor the growth of the Ag NCs into a quasi-spherical shape via its preferential adsorption on the NC {111} facets. The major role of citrate is to stabilize the newly formed NCs, whereas it has a minor contribution to reduction of AgNO3. The synergy of the effects of AA, citrate, and KI can significantly narrow the size distributions of the Ag NCs obtained so and transform the NC shapes to be truly quasi-spherical.

Monodisperse, quasi-spherical silver nanoparticles (Ag NPs) with controlled sizes have been produced directly in water via adding the aqueous solutions of the mixtures of AgNO3 and sodium citrate to boiling aqueous solutions of ascorbic acid (AA). Different compounds, including NaCl, NaBr, KI, Na2SO4, Na2CO3, Na2S, and Na3PO4, are added to the AgNO3/citrate mixture solutions to form new silver compounds with fairly low solubility in water, which are used as precursors instead of soluble Ag(+) ions to synthesize Ag NPs via AA/citrate reduction. This enables us not only to produce monodisperse, quasi-spherical Ag NPs but also to tune the sizes of the resulting NPs from 16 to 30 nm according to the potential of new silver precursors as well as the concentrations of anions.

Nanoporous gold freestanding films (NPG FSFs) have been fabricated via overgrowth of gold onto selfassembled monolayers of gold nanocrystals at planar fluid-fluid interfaces. The resulting NPG FSFs are ligand-free on their surfaces and their sizes can be as large as several cm 2 . The NPG FSFs are fairly mechanically robust; their effective Young's moduli are of the order of about 10 GPa. The NPG FSFs exhibit efficient electrocatalytic activity for methanol oxidation with an excellent electrochemical endurance, which is attributed to the presence of high-index facets on the curved surfaces of gold ligaments in the NPG FSFs. It is found that the catalytic performance of as-prepared NPG FSFs is related to the curved-to-flat surface area ratios of gold ligaments in NPG FSFs. The highly curved surface areas in the NPG FSFs can be increased via optimizing the concentration of HAuCl 4 and the citrate to HAuCl 4 molar ratio in the electroless plating solution.

We present a simple strategy for synthesis of water-soluble, monodisperse, highly fluorescent gold nanoclusters (Au NCs) with sizes of 1.8 nm by co-reduction of glutathione and citrate for 24 h at 50 °C. The fluorescence intensity of the GS/C–Au NCs obtained is pH-dependent and can be reversibly adjusted in the pH range from 4.1 to 8.6.

No abstract