Novel syntheses and behavior of precious metal nanoparticles
[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] In this work, I report the detailed syntheses of both gold-doped iron oxide (Au@Fe2O3) and silver nanocrystals (AgNCs). The Au@Fe2O3 was produced through ultrasonic spray pyrolysis (USP), a novel technique utilizing in-line ultrasonic humidifier, tube furnace, and collection vessel (construction of this apparatus is also explained for reproduction of the design). This Au@Fe2O3 demonstrated good catalytic activity in the model reduction of 4-nitrophenol and responded weakly to an external magnetic field, resulting in our proposed application as a reusable catalyst. Additionally, I present a visually-appealing nanochemistry demonstration suitable for an undergraduate or advanced high school chemistry curriculum. A solution of AgNCs is prepared in a 4:96 H2O:EtOH mixture, resulting in a vivid yellow colloid which slowly transitions to orange, red, violet, and finally blue as the AgNCs grow and aggregate before precipitating out of solution. The transition occurs over approximately 3 minutes, allowing ample time for the discussion of AgNC synthesis, growth, and surface chemistry. This pedagogical study of nanochemistry is ideal for establishing these topics in the minds of aspiring chemists.
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