Ultrasonic Alloying of Preformed Gold and Silver Nanoparticles

Abstract

Alloyed gold/silver nanoparticles with a core/shell structure are produced from preformed gold and silver nanoparticles during ultrasonic treatment at different intensities in water and in the presence of surface-active species. Preformed gold nanoparticles with an average diameter of 15 + or - 5 nm are prepared by the citrate reduction of chloroauric acid in water, and silver nanoparticles (38 + or - 7 nm) are formed after reduction of silver nitrate by sodium borohydride. Bare binary gold/silver nanoparticles with a core/shell structure are formed in aqueous solution after 1 h of sonication at high ultrasonic intensity. Cationic-surfactant-coated preformed gold and silver nanoparticles become gold/silver-alloy nanoparticles after 3 h of sonication in water at 55 W cm(-2), whereas only fusion of isolated gold and silver nanoparticles is observed after ultrasonic treatment in the presence of an anionic surfactant. As the X-ray diffraction profile of alloyed gold/silver nanoparticles reveals split, shifted, and disappeared peaks, the face-centered-cubic crystalline structure of the binary nanoparticles is defect-enriched by temperatures that can be as high as several thousand Kelvin inside the cavitation bubbles during ultrasonic treatment.

Green controllable synthesis of Au–Ag alloy nanoparticles using Chinese wolfberry fruit extract and their tunable photocatalytic activity

“…2, only one peak is exhibited in each UV-vis spectrum, which just illustrates synthesized NPs have an alloy structure rather than a core-shell structure or a mixture of monometallic NPs. 38 According to the inset of Fig. 3, the relationship between the SPR wavelength and the Au element molar fraction was tted linearly as follows:…”

Synthesis, characterization and in vitro effects of 7 nm alloyed silver–gold nanoparticles

“…Recently, the generation of alloyed silver–gold nanoparticles by laser ablation was reported [25–27]. Alloying of presynthesized silver core/gold shell nanoparticles by refluxing with oleylamine [28] or ultrasonication of separate gold and silver nanoparticles [29] was also described.…”

Metal-Based Composite Nanomaterials

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