Abstract
CHAPTER 1 Seed-Mediated Growth of Silver Nanocubess in Aqueous Solution In this work, we have developed a seed-mediated approach to synthesize Ag nanocubes with average edge lengths from 23 nm to 60 nm. Ag seed solution is added a growth solution containing CF3COOAg, cetyltrimethylammonium chloride (CTAC), and ascorbic acid. Ag nanocubes are synthesized by using ascorbic acid as reducing agent to reduce AgCl in the presence of CTAC. We have also used another method to synthesize Ag nanocubes. This approach involves adding the seed solution to a growth solution containing AgNO3, cetyltrimethylammonium bromide (CTAB), CuSO4 and ascorbic acid. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD) patterns have been employed to characterize the Ag nanocubes. UV‒vis absorption spectra of the particles have been obtained. CHAPTER 2 Formation of Au Nanocages from Ag Nanocubes and Their Photothermal Effect In this study, we have used Ag nanocubes as templates to synthesize Au nanocages by adding HAuCl4 at 30 ºC for 10 minutes. This involves galvanic replacement reaction. Ag nanocubes are oxidized and AuCl4‒ is reduced to Au and deposited on the surface of Ag nanocubes. When different amounts of HAuCl4 were added to a growth solution including Ag nanocubes and CTAC, the morphology and Au/Ag ratio can vary. We used the cages to investigate photothermal effect. Using different cages, the solution temperature can rise to 90, 95 and 100ºC under the illumination of an 808 nm laser with 1.47 W. Use of a 1064 nm laser led to a lower heating efficiency. These cages may find applications including heat generation for as an energy source.