Gold preparation procedure

Figure 4. Preparative procedure of alkene thiol-stabilized gold nanoparticles. 50% of hexenethiol bounded to the particle surface is hydrogenated to hexanethiol [11b].

An alternative or additional step to flame annealing is electrochemical or chemical polishing. The fundamental aspects of electropolishing were reviewed recently [185], and a list of polishing procedures and parameters is available [185,186]. This method has been successfully applied to the preparation of gold, silver, and copper electrodes for STM studies [177,180,188]. It is important to note that different mesoscopic structures may arise according to the specific preparation procedures. For example, electropolishing a mechanically prepared Au(lOO) surface followed by... 

The processes of sample preparation should not be too onerous or slow otherwise there is little incentive to use sensors. Faced with an awkward or slow sample preparation phase for sensor use, the analyst might as well as consider whether instrumental analyses with their often higher sensitivity and specificity (and which, in any case, are regarded as the gold standard for industrial measurements), coupled with on-line sample preparation procedures, might be a more efficient and effective route to chemical information. 

For gold to be an active catalyst, use of a careful preparation procedure is crucial in order to obtain it as nanoparticles well dispersed on the oxide support. In this section we describe the methods devised for the preparation of these nanoparticulate gold catalysts. Catalysts are thought to be most active in the 2- to 5-nm gold particle range but both smaller and larger particles have also been shown to have activity and may play a significant role. 

A major hurdle towards understanding the unusual low temperature CO oxidation activities of supported Au catalysis is that there is a wide variation in the reported CO oxidation activities over these catalysts [5]. This arises because these catalysts are very sensitive to the preparation procedures. Most supported Au catalysts are prepared with the chloride-containing chloroauric acid precursor, although there have been recent attempts to prepare these catalysts with precursors such as dimethyl gold acetonate [6], gold-phosphine complexes [7], and gold ethylene diamine complexes [8]. This discussion will focus on the complications that arise with chloride-containing precursors. 

Fig. 2 Typical preparation procedures of template-stripped gold surfaces supported (a) by a piece of silicon wafer and (b) by a glass coverslip [165].

FIGURE 42.22 SIMS Analysis of rat brain tissue sections with different projectiles (E = 20 keV) and sample preparation procedures ( native, no sample pretreatment gold, sputter-coated with 1 nm of Au matrix, deposition of a thin layer of 2,5-DHB with a pneumatic sprayer). Relative intensities of ions are in the range m/z > 600. Figure from Reference [319]. 

Dammer et al. [4] also worked with metal nanoparticles and showed the importance of preparation procedure on the optical properties of polymer nanocomposites with gold nanoparticles. Similar to other properties, optical properties depend on the dispersion of nanoparticles caused by the processing conditions. 

Figure 46.8 Preparation procedure of gold nanopartide/silica core/shell MIPs. (Adapted with permission from Ref. [29].)...

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