Ultrasonic Alloying of Preformed Gold and Silver Nanoparticles
Ultrasonic Alloying of Preformed Gold and Silver Nanoparticles
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DOI：
10.1002/smll.200901623
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发表时间：
2010-02-22
期刊：
影响因子：
13.3
通讯作者：
Moehwald, Helmuth
中科院分区：
文献类型：
--
作者：
Radziuk, Darya V.;Zhang, Wei;Moehwald, Helmuth
具有核/壳结构的合金金/银纳米颗粒是由预制的金和银纳米颗粒在水中以不同强度和表面活性物质存在的情况下进行超声波处理而产生的。通过氯金酸在水中的柠檬酸盐还原制备平均直径为15+/-5nm的预制金纳米颗粒，通过硼氢化钠还原硝酸银后形成银纳米颗粒(38+/-7nm)。在高超声强度下超声处理 1 小时后，在水溶液中形成具有核/壳结构的裸二元金/银纳米颗粒。涂覆有阳离子表面活性剂的预制金和银纳米颗粒在55 W cm(-2)水中超声处理3 h后变成金/银合金纳米颗粒，而在阴离子表面活性剂存在下超声处理后仅观察到孤立的金和银纳米颗粒的融合。由于合金金/银纳米颗粒的 X 射线衍射图显示了分裂、移动和消失的峰，因此二元纳米颗粒的面心立方晶体结构在超声波处理过程中空化气泡内高达数千开尔文的温度下缺陷丰富。
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 +/- 5 nm are prepared by the citrate reduction of chloroauric acid in water, and silver nanoparticles (38 +/- 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.