Adsorption on semiconductors

From the theoretical standpoint the above issues are addressed by quantum chemistry. On the basis of calculations of various cluster models [191] the properties of surfaces of solid body are being studied as well as issues dealing with interaction of gas with the surface of adsorbent. However, fairly good results have been obtained in this area only to calculate adsorption on metals. The necessity to account for more complex structure of the adsorption value as well as availability of various functional groups on the surface of adsorbent in case of adsorption on semiconductors geometrically complicates such calculations. 

The conclusion of the study [89] concerning non-dissociated character of hydrogen adsorption on semiconductors of ZnO type at low temperatures (lower than 70 C) was based on experimental facts indicating that hydrogen atoms which independently arrive at the surface of semi-... 

As described in the preceding sections, fundamental studies of heterogeneous catalysis at the surface of catalysts are important for understanding reaction pathways and for the development of new or improved catalysts and processes. There have been earlier hypotheses proposed for selective oxidation catalysis for example, the multiplet theory which suggests that the activity depends upon correctly spaced groups (multiplets) of atoms to accommodate the reactant molecule (Balandin, 1969) and electronic theory based on the nature of adsorption on semiconductors and empirical correlations between activity, work function and electrical conductivity (Wolkenstein 1960). The importance... 

Whilst in a qualitative sense this theory has a certain basic validity, it does not provide very real physical insight into the electronic and structural effects now known to be associated with adsorption on semiconductors. In the following sections, we shall attempt to show how the subject has been developed from the much greater understanding of semiconductor surfaces which is now available. 

To a chemist, the latter point is extremely significant since chemical potential is a thermodynamic term, and can, in general, be related to all types of chemical reactions whether they be acid/base reactions, electrode reactions or phase transitions. Of particular Interest will be the similarities to adsorption on semiconductors. 

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