Molybdenum disulfide, adsorbed

Molybdenum disulfide has a layered structure. Each layer is a sandwich consisting of between two layers of ions (Fig. 9.5). The sulfur ions form trigonal prisms and half of the prisms contain a molybdenum ion in the middle. The chemical reactivity of M0S2 is associated with the edges of the sandwich, whereas the basal planes are much less reactive. The edges form the sites where gases adsorb and where the catalytic activity resides. 

The publications are listed in two different ways Table A4.1 is alphabetical by common or systematic name, thus acetone not propanone, propylene not propene. The formula is given in the usual style, thus Fe(CO)s not FeCsOs. Catalyst studies are listed in two ways under the name of the adsorbate, with the entry starting with. Thus the next entry after thiophene is M0S2, showing that thiophene on M0S2 has been studied. Catalyst studies are also listed under the name of the catalyst so there is an entry for molybdenum disulfide with H2 and thiophene. The two types of entry allow the reader to find all the molecules that have been studied on a particular catalyst or all the catalysts a particular molecule has been studied on. Hydrogen is subdivided into systems where H2 was the species studied e.g. H2 on Ru/C or... 

It is thus seen that the interaction of molybdenum disulfide with its ambient surroundings in a tribological context involves complexities that have not been fully resolved. It has not been established why the friction of rubbed M0S2 should be adversely affected by adsorbed water vapor. Speculations range from the formation of intercalation structures... 

Molybdenum disulfide has a layered structure consisting of Mo with a formal oxidation state of 4+, trigonally coordinated by sulfur anions. The basal plane of this structure is virtually unreactive, all activity is associated with the edges of the slabs (Figure 3.13). These are the sites where adsorption takes place. O2, CO and NO are among the gases which have been shown to adsorb at these sites. Hydrogen is easily activated by sulfides, and dissociates readily under reactions conditions. 

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