I am working on my course project titled " Laser induced assembly of gold nano particles into colloidal crystals". We are synthesising gold nano particles by nanopulsed laser(Nd-YAG second harmonic) ablation. How Laser parameters - wavelength,pulse width,fluence,repetition rate,scanning time affects the size and efficiency of the nanoparticles and which are the values for these factors to get maximum efficiency? we need to get nanoparticles have an average size less than 20nm.please help me.Read more…
Due to its largely nonreactive nature gold has long been considered a “noble” metal, undergoing few of the reactions of its transition metal counterparts. This assumption of considering gold catalytically inert changed, however, in the late 90s after the seminal contribution of Haruta, who reported that gold nanoparticles are extremely active in promoting the low - temperature, aerobic oxidation of CO to CO2 (Fig 1)  . Moreover, Haruta and co-workers showed that the catalytic activity of gold appears for particles in the nanometric size range, there being a direct relationship between activity and particle diameter . Since this breakthrough, research has been aimed at determining the reaction types that can be efficiently catalyzed by nanometric gold particles, increasing the catalytic activity of gold by stabilizing nanoparticles against agglomeration, understanding the role of the solid support in the catalytic activity and also demonstrating the similarities and distinctive properties of gold catalysis with respect to catalysis by other noble metals.
Fig 1: Schematic illustration of one of the coadsorption and catalytic combustion cycles.
The importance of gold nanoparticles in catalysis derives in part from the wealth of information and reliable experimental procedures to form these nanoparticles in different sizes and, even different shapes .
1- Haruta, M., T. Kobayashi, et al. (1987). "Novel Gold Catalysts for the Oxidation of Carbon Monoxide at a Temperature far Below 0 °C " Chemistry Letters 16: 405-40
2- Haruta, M. (1997). "Size- and support-dependency in the catalysis of gold " Catalysis Today ( 36 ): 153-166.
3- Astruc, M.-C. D. a. D. ( 2004). "Gold Nanoparticles: Assembly, Supramolecular Chemistry, Quantum-Size-Related Properties, and Applications toward Biology, Catalysis, and Nanotechnology." Chem. Rev. 293-346 104: 293-346
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preparation of gold nanoparticlec There are basically two different procedures to form gold nanoparticles, depending on whether they are going tobe dispersed in a liquid or supported on a solid. In spite of the fact that the formation of gold nanoparticles was known since ancient times (Astruc 2004), many researchers consider that the first systematicstudy of the formation of colloidal gold nanoparticles started with thepioneering work of Turkevich (Turkevicph, Stevensoan et al. 1951),…Read more…
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