Keggin Ions as UV-Switchable Reducing Agents in the Synthesis of Au Core−Ag Shell Nanoparticles

• Published in: Journal of the American Chemical Society Vol. 125; no. 28; pp. 8440 - 8441
• Main Authors: Mandal, Saikat, Selvakannan, PR, Pasricha, Renu, Sastry, Murali
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 16.07.2003
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Gold chloride; Heteropolyacid; Silver sulfate; Transmission electron microscopy; Near ultraviolet radiation; Transition metal Compounds; Spherical particle; Aqueous solution; Particle suspension; Experimental study; Metal particle; Submicron particle
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja034972t

Keggin ion-mediated synthesis of Au core−Ag shell bimetallic nanoparticles is described. Exposure of photochemically reduced aqueous (PW12O40)3- Keggin ions to AuCl4 - ions leads to the formation of stable gold nanoparticles capped by the Keggin ions. The surface-bound Keggin ions may then be activated by UV irradiation and, upon exposure to Ag+ ions, reduce the metal ions to form a silver shell around the gold core. That the capping agent not only stabilizes the metal nanoparticles but also plays the role of a switchable reducing agent is a highlight of this approach with important implications in nanomaterials synthesis and catalysis.