Surface Chemistry of Gold

In this section, the surface chemistry of non-metals adsorbed as thin layers, films or SAMs on gold surfaces is discussed. Although attachment by a sulfur atom is by far the most predominant binding motif, many other elements may be used to bind to gold. Particular focus is given here to surface binding through atoms other than those already extensively covered in the literature. 

The hydrogen molecule does not chemisorb onto clean sintered gold surfaces at or above 78 K [147] but on unsintered films, a small amount of H2 is chemisorbed if gold surface atoms of low coordination number are present [148]. Stobinski [149] found that H2 can also chemisorb on thin sintered Au films if the surface is covered at low temperatures with a small amount of gold equivalent to 1-3 Au monolayers prior to H2 exposure. This suggests a fundamental role of surface Au atoms of low coordination number in the chemisorption process. Deuterium molecules also chemisorb in a similar fashion on gold films at 78 K and isotope effects were 

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Chen, X. (1998) Control of surface chemistry of gold, pyrite and pyrrhotite. Master thesis, Virginia Polytechnic Institute and State University, Blacksburg. 

Theoretical Chemistry of Gold - From Atoms to Molecules, Clusters, Surfaces and the Solid State... 

Mulvaney P, Giersig M, Henglein A (1992) Surface chemistry of colloidal gold deposition of lead and accompanying optical effects. J Phys Chem 96 10419-10424... 

D.C. Meier, X. Lai, and D.W. Goodman, Surface chemistry of model oxide-supported metal catalysts An overview of gold on Titania, in Surface Chemistry and Catalysis, eds. A.F. Carley et al. Kluwer, New York, 2002, pp. 147-189. 

In this section, we will emphasize how the different chemical approaches allow control over the size, shape and assembly of Au NPs. The first subsection describes the most common synthetic approaches for the synthesis of gold nanoparticles, based on historically known methods from Faraday and Turkevitch. The surface chemistry of Au NPs, Au nano-bio hybrids synthesis and certain properties and applications of gold nanoparticles will be briefly summarized. 

Nearly all the experiments described were performed in an ultra high vacuum chamber at pressures of about 10 10 torr. The specific equipment and experimental procedures used have been described elsewhere (7-9). Experimental protocol for the thermal desorption experiments and for the chemical displacement reactions is presented below. All these experiments were repeated with a control, blank experiment with a metal crystal that had the front and exposed face covered with gold the sides and back of the crystal were exposed (8,9). These blank experiments were performed to ensure that all thermal desorption and chemical displacement experiments monitored only the surface chemistry of the front exposed face of the metal crystal under study. 

Meyer R, Lemire C, Shaikhutdinov S, Freund HJ (2004) The surface chemistry of catalysis by gold. Gold Bull 37 72... 

Chen, S.W. and Murray, R.W. (1999) Electrochemical quantized capacitance charging of surface ensembles of gold nanopartides. Journal of Physical Chemistry B, 103, 9996-10000. 

High-nuclearity clusters of the transition metals and a re-evaluation of the cluster-surface analogy Recent developments in the cluster chemistry of gold... 

The knowledge of the colloidal chemistry of gold was used by Kim and Turkevich(106) to prepare monodisperse palladium particles in diameter greater than 75 A. The number of surface atoms determined by electron microscopy was found to be equal to the number of catalytic centers determined by poison titration for the athylene hydrogenation reaction. The surface of the palladium catalyst was homogenous. The velocity of the catalytic reaction was found to be proportional to the number of surface atoms. All surface atoms were active. 

Fig. 6.2 This sequence of images highlights the impact of the underlying substrate on an overlaying polymer film. The films were made from a polymer blend solution where the polymer blend ratio and the processing conditions were kept constant. The images are atomic force microscopy height images and show where the polymers have segregated. In each sample the substrate surface chemistry, originally gold, was coated with a different self-assembled molecule layer to form various surface chemistries. Reprinted with permission [6]...

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