An Investigation of the Electrochemistry of a Series of Metal Dioxides with Rutile‐Type Structure: MoO2, WO 2, ReO2, RuO2, OsO2, and IrO2

Six transition metal dioxides, , , , , , and , have been examined as electrodes in solution. The oxides , , , and have broad current‐potential profiles, indicating the formation of a surface layer which can exist over a range of compositions. Steady‐state measurements of reduction showed catalytic activities which were low compared to common catalysts such as Pt, but of the same order as other oxide catalysts. Activities were lowest for and , which form resistive surface layers of a higher oxide. The only material studied which was sufficiently stable to allow measurement of both evolution and reduction was . The current‐potential profiles of and are characterized by distinct changes of oxidation state. These two oxides were not sufficiently stable to allow the measurement of reduction.