The catalytic properties and structure of metal films.—Part I. Sputtered platinum

Abstract

During an experimental study by Stimson and one of us of the electrical condition of a platinum sheet, it was found that the surface sometimes exhibited a charge at room temperature after a previous treatment consisting, in the main, of heating in oxygen and hydrogen alternately. It was found later that cathodically sputtered platinum films were not only frequently electrically charged at room temperature, but were also sometimes exceedingly active catalysts of the union of hydrogen and oxygen at room temperature. In the course of these experiments, it soon became evident that the conditions under which the sputtered films were prepared in some manner profoundly affected their catalytic properties, and the following investigation was therefore carried out with the object, inter alia , of determining in what manner and to what extent sputtering conditions influenced the catalytic and structural properties of the resulting films. The experiments of which an account is now given in the ensuing first part of this communication were begun by two of us (G. I. F. and N. S.) in September, 1929. Both catalytically active and inactive films were obtained, and the sputtering conditions determining their production sufficiently well defined to enable the different types of surface to be prepared at will. It soon became evident, however, that the activity or otherwise of the films was in some manner intimately associated with structural properties which, owing to their submicroscopic nature, defied direct examination by the means then at our disposal.