ELECTROCHEMICAL AND SURFACE SPECTROSCOPIC STUDIES OF THIN-FILMS OF BISMUTH RUTHENIUM OXIDE (BI2RU2O7)

Thin, nonporous films of bismuth ruthenium oxide having the pyrochlore crystal structure were prepared by ion beam deposition. The films wer e grown on metal disks machined to fit into a rotating: ring-disk elec trode. The electrocatalytic properties of these films for O-2 reductio n and evolution were studied in 1 M KOH using the rotating ring-disk e lectrode method in conjunction with spectroscopic studies of the surfa ces before and after electrochemical analysis. The crystalline pyrochl ore film was found to be an extremely poor oxygen reduction catalyst, but it could be activitated in situ by a procedure that created a high ly porous amorphous structure by dissolution of bismuth cations into t he solution. We found in separate experiments that bismuth ions in sol ution increased the oxygen reduction activity of a nonporous ruthenium oxide surface, and suggest that there is an analogous effect on the a ctivity of the residual, ruthenium-rich oxide surface by bismuth ions in solution following activation.