The Ionic Adsorption of Gases on Semi-Conductors and Their Catalytic Activities

In the present paper a general theory of ionic adsorption of gases on semi-conductors is developed, with particular consideration for the combination of the types of semi-conductors and the signs of the electric charge on the adsorbed molecules. The results obtained agree qualitatively with experiments, but contradict predictions made by DOWDEN who in his theory does not take the space-charge layer near the surface into account. In the last section, physical models for adsorption sites are speculatively considered. A discussion of the catalytic activities of semi-conductors based on the present theory of adsorption is given. The applications to special reaction systems will be given in Part II of the present series.