Nano-objects synthesized from Cu, Ag and Cu28Ag72 electrodes by submerged discharges in liquid nitrogen.

Discharges in liquid nitrogen between 2 electrodes made of either Cu, Ag or Cu 28 Ag 72 enable the production of several types of comparable nano-objects. First, Cu nanoparticles (NPs) with sizes close to 5 ± 4 nm nm and 40 ± 10 nm are obtained with Cu electrodes and get oxidized in the air to form CuO after liquid evaporation. With Cu 28 Ag 72 electrodes, copper contains a small amount of silver that inhibits oxidation. Next, silver nanoparticles are spherical but when doped with copper, they are facetted. Silver-containing nanowires have very similar features whether they are synthesized with silver or CuAg electrodes. They are made by assembly of NPs. Ag nanosheets are either single crystals in the case of CuAg electrodes or assembly of NPs in the case of silver electrodes. Finally, silver nanorods with traces of copper are only found with CuAg electrodes. Time-resolved optical emission spectroscopy indicates that the optical thickness decreases when copper is added to silver, lines appearing immediately after breakdown and not only after emission of a broad continuum. Emission of lines belonging to the N II system is then observed. The energy deposited being nearly constant, the structure of the discharge is assumed to be changed. [ABSTRACT FROM AUTHOR]