Characterisation of Metallic Surfaces and Metal Nanoparticles

As already discussed, the size, the shape and the dispersion are characteristic parameters of metal particles and will determine their properties. It is possible to characterize them as follows (i) The size of the metal particles (transmission electron microscopy, (TEM) [79-81], extended X-ray absorption fine structure (EXAFS) [82, 83]), (ii) their structures (X-ray diffraction (XRD), TEM), (iii) their chemical composition (TEM-EDX, elemental analysis), (iv) the chemical state of the surface and bulk metal atoms (X-ray photoelectron spectroscopy (XPS)), Mossbauer [84], thermo-programmed-reduction (TPR)), (v) chemisorption capacity toward probe molecules such as H2, O2, NO and CO (volumetric or dynamic measurements) [85-90]. 

In the case of metal surfaces, metallic particles can be obtained in three different states  

The bulk and surface atoms in the particles are represented respectively by M and Mg. 

The stoichiometry of the hydrogen adsorption capacity (value of x) depends on the nature of the metal, on the temperature of the adsorption and on the H2 pressure. 

Depending on the nature of the metal and on the temperature of the oxidizing treatment, all the metal atoms can be oxidized, or in some cases only the surface atoms are oxidized. The oxidized metal atoms are represented by (bulk) or (surface), where (X) is the oxidation state of 

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