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

Abstract

In Part I of the present work the theory of ionic adsorption was developed. In the present paper, the theory of the catalytic activity of semi-conductors is extended on the basis of the previous conclusions as to the ionic adsorption of gases. By introducing the concept of a “virtual atmosphere”, a guiding principle for the selection of catalysts is obtained. The law of the virtual atmosphere here derived is applied to the oxidation of carbon monoxide on a semi-conductor, and provides the reasons the RIDEAL mechanism in this reaction is observed not on n-type but on p-type semi-conductor catalysts. Moreover, the relation between the catalytic activity and the history of a sample is reasonably interpreted in terms of the virtual atmosphere. Other reactions such as the decomposition of nitrous oxide and the synthesis of methanol are discussed qualitatively.